diff --git a/src/GraphQL/Client.php b/src/GraphQL/Client.php
index 9c039d5..4f1df80 100644
--- a/src/GraphQL/Client.php
+++ b/src/GraphQL/Client.php
@@ -325,257 +325,257 @@ public function workCount(): int
 
     public function createAffiliation(Affiliation $affiliation): string
     {
-        return $this->mutation('createAffiliation', $affiliation, 'affiliationId');
+        return $this->mutation('createAffiliation', $affiliation->getAllData(), 'affiliationId');
     }
 
     public function updateAffiliation(Affiliation $affiliation): string
     {
-        return $this->mutation('updateAffiliation', $affiliation, 'affiliationId');
+        return $this->mutation('updateAffiliation', $affiliation->getAllData(), 'affiliationId');
     }
 
-    public function deleteAffiliation(Affiliation $affiliation): string
+    public function deleteAffiliation(string $affiliationId): string
     {
-        return $this->mutation('deleteAffiliation', $affiliation, 'affiliationId');
+        return $this->mutation('deleteAffiliation', ['affiliationId' => $affiliationId], 'affiliationId');
     }
 
     public function createContribution(Contribution $contribution): string
     {
-        return $this->mutation('createContribution', $contribution, 'contributionId');
+        return $this->mutation('createContribution', $contribution->getAllData(), 'contributionId');
     }
 
     public function updateContribution(Contribution $contribution): string
     {
-        return $this->mutation('updateContribution', $contribution, 'contributionId');
+        return $this->mutation('updateContribution', $contribution->getAllData(), 'contributionId');
     }
 
-    public function deleteContribution(Contribution $contribution): string
+    public function deleteContribution(string $contributionId): string
     {
-        return $this->mutation('deleteContribution', $contribution, 'contributionId');
+        return $this->mutation('deleteContribution', ['contributionId' => $contributionId], 'contributionId');
     }
 
     public function createContributor(Contributor $contributor): string
     {
-        return $this->mutation('createContributor', $contributor, 'contributorId');
+        return $this->mutation('createContributor', $contributor->getAllData(), 'contributorId');
     }
 
     public function updateContributor(Contributor $contributor): string
     {
-        return $this->mutation('updateContributor', $contributor, 'contributorId');
+        return $this->mutation('updateContributor', $contributor->getAllData(), 'contributorId');
     }
 
-    public function deleteContributor(Contributor $contributor): string
+    public function deleteContributor(string $contributorId): string
     {
-        return $this->mutation('deleteContributor', $contributor, 'contributorId');
+        return $this->mutation('deleteContributor', ['contributorId' => $contributorId], 'contributorId');
     }
 
     public function createFunding(Funding $funding): string
     {
-        return $this->mutation('createFunding', $funding, 'fundingId');
+        return $this->mutation('createFunding', $funding->getAllData(), 'fundingId');
     }
 
     public function updateFunding(Funding $funding): string
     {
-        return $this->mutation('updateFunding', $funding, 'fundingId');
+        return $this->mutation('updateFunding', $funding->getAllData(), 'fundingId');
     }
 
-    public function deleteFunding(Funding $funding): string
+    public function deleteFunding(string $fundingId): string
     {
-        return $this->mutation('deleteFunding', $funding, 'fundingId');
+        return $this->mutation('deleteFunding', ['fundingId' => $fundingId], 'fundingId');
     }
 
     public function createImprint(Imprint $imprint): string
     {
-        return $this->mutation('createImprint', $imprint, 'imprintId');
+        return $this->mutation('createImprint', $imprint->getAllData(), 'imprintId');
     }
 
     public function updateImprint(Imprint $imprint): string
     {
-        return $this->mutation('updateImprint', $imprint, 'imprintId');
+        return $this->mutation('updateImprint', $imprint->getAllData(), 'imprintId');
     }
 
-    public function deleteImprint(Imprint $imprint): string
+    public function deleteImprint(string $imprintId): string
     {
-        return $this->mutation('deleteImprint', $imprint, 'imprintId');
+        return $this->mutation('deleteImprint', ['imprintId' => $imprintId], 'imprintId');
     }
 
     public function createInstitution(Institution $institution): string
     {
-        return $this->mutation('createInstitution', $institution, 'institutionId');
+        return $this->mutation('createInstitution', $institution->getAllData(), 'institutionId');
     }
 
     public function updateInstitution(Institution $institution): string
     {
-        return $this->mutation('updateInstitution', $institution, 'institutionId');
+        return $this->mutation('updateInstitution', $institution->getAllData(), 'institutionId');
     }
 
-    public function deleteInstitution(Institution $institution): string
+    public function deleteInstitution(string $institutionId): string
     {
-        return $this->mutation('deleteInstitution', $institution, 'institutionId');
+        return $this->mutation('deleteInstitution', ['institutionId' => $institutionId], 'institutionId');
     }
 
     public function createIssue(Issue $issue): string
     {
-        return $this->mutation('createIssue', $issue, 'issueId');
+        return $this->mutation('createIssue', $issue->getAllData(), 'issueId');
     }
 
     public function updateIssue(Issue $issue): string
     {
-        return $this->mutation('updateIssue', $issue, 'issueId');
+        return $this->mutation('updateIssue', $issue->getAllData(), 'issueId');
     }
 
-    public function deleteIssue(Issue $issue): string
+    public function deleteIssue(string $issueId): string
     {
-        return $this->mutation('deleteIssue', $issue, 'issueId');
+        return $this->mutation('deleteIssue', ['issueId' => $issueId], 'issueId');
     }
 
     public function createLanguage(Language $language): string
     {
-        return $this->mutation('createLanguage', $language, 'languageId');
+        return $this->mutation('createLanguage', $language->getAllData(), 'languageId');
     }
 
     public function updateLanguage(Language $language): string
     {
-        return $this->mutation('updateLanguage', $language, 'languageId');
+        return $this->mutation('updateLanguage', $language->getAllData(), 'languageId');
     }
 
-    public function deleteLanguage(Language $language): string
+    public function deleteLanguage(string $languageId): string
     {
-        return $this->mutation('deleteLanguage', $language, 'languageId');
+        return $this->mutation('deleteLanguage', ['languageId' => $languageId], 'languageId');
     }
 
     public function createLocation(Location $location): string
     {
-        return $this->mutation('createLocation', $location, 'locationId');
+        return $this->mutation('createLocation', $location->getAllData(), 'locationId');
     }
 
     public function updateLocation(Location $location): string
     {
-        return $this->mutation('updateLocation', $location, 'locationId');
+        return $this->mutation('updateLocation', $location->getAllData(), 'locationId');
     }
 
-    public function deleteLocation(Location $location): string
+    public function deleteLocation(string $locationId): string
     {
-        return $this->mutation('deleteLocation', $location, 'locationId');
+        return $this->mutation('deleteLocation', ['locationId' => $locationId], 'locationId');
     }
 
     public function createPrice(Price $price): string
     {
-        return $this->mutation('createPrice', $price, 'priceId');
+        return $this->mutation('createPrice', $price->getAllData(), 'priceId');
     }
 
     public function updatePrice(Price $price): string
     {
-        return $this->mutation('updatePrice', $price, 'priceId');
+        return $this->mutation('updatePrice', $price->getAllData(), 'priceId');
     }
 
-    public function deletePrice(Price $price): string
+    public function deletePrice(string $priceId): string
     {
-        return $this->mutation('deletePrice', $price, 'priceId');
+        return $this->mutation('deletePrice', ['priceId' => $priceId], 'priceId');
     }
 
     public function createPublication(Publication $publication): string
     {
-        return $this->mutation('createPublication', $publication, 'publicationId');
+        return $this->mutation('createPublication', $publication->getAllData(), 'publicationId');
     }
 
     public function updatePublication(Publication $publication): string
     {
-        return $this->mutation('updatePublication', $publication, 'publicationId');
+        return $this->mutation('updatePublication', $publication->getAllData(), 'publicationId');
     }
 
-    public function deletePublication(Publication $publication): string
+    public function deletePublication(string $publicationId): string
     {
-        return $this->mutation('deletePublication', $publication, 'publicationId');
+        return $this->mutation('deletePublication', ['publicationId' => $publicationId], 'publicationId');
     }
 
     public function createPublisher(Publisher $publisher): string
     {
-        return $this->mutation('createPublisher', $publisher, 'publisherId');
+        return $this->mutation('createPublisher', $publisher->getAllData(), 'publisherId');
     }
 
     public function updatePublisher(Publisher $publisher): string
     {
-        return $this->mutation('updatePublisher', $publisher, 'publisherId');
+        return $this->mutation('updatePublisher', $publisher->getAllData(), 'publisherId');
     }
 
-    public function deletePublisher(Publisher $publisher): string
+    public function deletePublisher(string $publisherId): string
     {
-        return $this->mutation('deletePublisher', $publisher, 'publisherId');
+        return $this->mutation('deletePublisher', ['publisherId' => $publisherId], 'publisherId');
     }
 
     public function createReference(Reference $reference): string
     {
-        return $this->mutation('createReference', $reference, 'referenceId');
+        return $this->mutation('createReference', $reference->getAllData(), 'referenceId');
     }
 
     public function updateReference(Reference $reference): string
     {
-        return $this->mutation('updateReference', $reference, 'referenceId');
+        return $this->mutation('updateReference', $reference->getAllData(), 'referenceId');
     }
 
-    public function deleteReference(Reference $reference): string
+    public function deleteReference(string $referenceId): string
     {
-        return $this->mutation('deleteReference', $reference, 'referenceId');
+        return $this->mutation('deleteReference', ['referenceId' => $referenceId], 'referenceId');
     }
 
     public function createSeries(Series $series): string
     {
-        return $this->mutation('createSeries', $series, 'seriesId');
+        return $this->mutation('createSeries', $series->getAllData(), 'seriesId');
     }
 
     public function updateSeries(Series $series): string
     {
-        return $this->mutation('updateSeries', $series, 'seriesId');
+        return $this->mutation('updateSeries', $series->getAllData(), 'seriesId');
     }
 
-    public function deleteSeries(Series $series): string
+    public function deleteSeries(string $seriesId): string
     {
-        return $this->mutation('deleteSeries', $series, 'seriesId');
+        return $this->mutation('deleteSeries', ['seriesId' => $seriesId], 'seriesId');
     }
 
     public function createSubject(Subject $subject): string
     {
-        return $this->mutation('createSubject', $subject, 'subjectId');
+        return $this->mutation('createSubject', $subject->getAllData(), 'subjectId');
     }
 
     public function updateSubject(Subject $subject): string
     {
-        return $this->mutation('updateSubject', $subject, 'subjectId');
+        return $this->mutation('updateSubject', $subject->getAllData(), 'subjectId');
     }
 
-    public function deleteSubject(Subject $subject): string
+    public function deleteSubject(string $subjectId): string
     {
-        return $this->mutation('deleteSubject', $subject, 'subjectId');
+        return $this->mutation('deleteSubject', ['subjectId' => $subjectId], 'subjectId');
     }
 
     public function createWork(Work $work): string
     {
-        return $this->mutation('createWork', $work, 'workId');
+        return $this->mutation('createWork', $work->getAllData(), 'workId');
     }
 
     public function updateWork(Work $work): string
     {
-        return $this->mutation('updateWork', $work, 'workId');
+        return $this->mutation('updateWork', $work->getAllData(), 'workId');
     }
 
-    public function deleteWork(Work $work): string
+    public function deleteWork(string $workId): string
     {
-        return $this->mutation('deleteWork', $work, 'workId');
+        return $this->mutation('deleteWork', ['workId' => $workId], 'workId');
     }
 
     public function createWorkRelation(WorkRelation $workRelation): string
     {
-        return $this->mutation('createWorkRelation', $workRelation, 'workRelationId');
+        return $this->mutation('createWorkRelation', $workRelation->getAllData(), 'workRelationId');
     }
 
     public function updateWorkRelation(WorkRelation $workRelation): string
     {
-        return $this->mutation('updateWorkRelation', $workRelation, 'workRelationId');
+        return $this->mutation('updateWorkRelation', $workRelation->getAllData(), 'workRelationId');
     }
 
-    public function deleteWorkRelation(WorkRelation $workRelation): string
+    public function deleteWorkRelation(string $workRelationId): string
     {
-        return $this->mutation('deleteWorkRelation', $workRelation, 'workRelationId');
+        return $this->mutation('deleteWorkRelation', ['workRelationId' => $workRelationId], 'workRelationId');
     }
 
     public function rawQuery(string $rawQuery, array $args = []): array
@@ -624,9 +624,9 @@ private function getByDoi(string $entityName, string $doi): AbstractModel
         return new $entityClass($result[$queryName]);
     }
 
-    private function mutation(string $mutationName, AbstractModel $mutationObject, string $returnValue): string
+    private function mutation(string $mutationName, array $data, string $returnValue): string
     {
-        $mutation = MutationBuilder::build($mutationName, $mutationObject->getAllData());
+        $mutation = MutationBuilder::build($mutationName, $data);
         $response = $this->request->runQuery($mutation, null, $this->token);
         $data = $response->getData();
         return $data[$mutationName][$returnValue];
diff --git a/src/GraphQL/MutationBuilder.php b/src/GraphQL/MutationBuilder.php
index a4d30b1..54b3b33 100644
--- a/src/GraphQL/MutationBuilder.php
+++ b/src/GraphQL/MutationBuilder.php
@@ -4,13 +4,14 @@
 
 class MutationBuilder
 {
-    public static function build(string $mutationName, array $mutationData, bool $nested = true): string
+    public static function build(string $mutationName, array $mutationData): string
     {
         $mutationFields = self::getMutationFields($mutationName);
         if ($mutationFields === null) {
             throw new \InvalidArgumentException("Mutation '{$mutationName}' not found.");
         }
 
+        $nested = !str_contains($mutationName, 'delete');
         $fields = $mutationFields['fields'];
         $returnValue = $mutationFields['returnValue'];
         $data = self::prepareData($fields, $mutationData);
diff --git a/tests/GraphQL/ClientTest.php b/tests/GraphQL/ClientTest.php
index 8dcd525..e132c69 100644
--- a/tests/GraphQL/ClientTest.php
+++ b/tests/GraphQL/ClientTest.php
@@ -1095,8 +1095,7 @@ public function testDeleteAffiliation(): void
             ]
         ])));
 
-        $affiliation = new Affiliation();
-        $result = $this->client->deleteAffiliation($affiliation);
+        $result = $this->client->deleteAffiliation('e435b256-681c-4118-a3b5-bba22cb6fe7f');
         $this->assertSame('e435b256-681c-4118-a3b5-bba22cb6fe7f', $result);
     }
 
@@ -1140,8 +1139,7 @@ public function testDeleteContribution(): void
             ]
         ])));
 
-        $contribution = new Contribution();
-        $result = $this->client->deleteContribution($contribution);
+        $result = $this->client->deleteContribution('5448ca99-ae7d-4347-9170-b8ffa067ebbf');
         $this->assertSame('5448ca99-ae7d-4347-9170-b8ffa067ebbf', $result);
     }
 
@@ -1185,8 +1183,7 @@ public function testDeleteContributor(): void
             ]
         ])));
 
-        $contributor = new Contributor();
-        $result = $this->client->deleteContributor($contributor);
+        $result = $this->client->deleteContributor('2724eca4-0d31-44ba-bbf4-19061a9637ce');
         $this->assertSame('2724eca4-0d31-44ba-bbf4-19061a9637ce', $result);
     }
 
@@ -1230,8 +1227,7 @@ public function testDeleteFunding(): void
             ]
         ])));
 
-        $funding = new Funding();
-        $result = $this->client->deleteFunding($funding);
+        $result = $this->client->deleteFunding('bba5f263-3442-4a4e-8b2b-752a238b9c03');
         $this->assertSame('bba5f263-3442-4a4e-8b2b-752a238b9c03', $result);
     }
 
@@ -1275,8 +1271,7 @@ public function testDeleteImprint(): void
             ]
         ])));
 
-        $imprint = new imprint();
-        $result = $this->client->deleteImprint($imprint);
+        $result = $this->client->deleteImprint('7485750d-c8cf-4a7e-9a6c-c080b932dbd9');
         $this->assertSame('7485750d-c8cf-4a7e-9a6c-c080b932dbd9', $result);
     }
 
@@ -1320,8 +1315,7 @@ public function testDeleteInstitution(): void
             ]
         ])));
 
-        $institution = new Institution();
-        $result = $this->client->deleteInstitution($institution);
+        $result = $this->client->deleteInstitution('a71debc6-0172-4cf5-b4c4-f932915ffce3');
         $this->assertSame('a71debc6-0172-4cf5-b4c4-f932915ffce3', $result);
     }
 
@@ -1365,8 +1359,7 @@ public function testDeleteIssue(): void
             ]
         ])));
 
-        $issue = new Issue();
-        $result = $this->client->deleteIssue($issue);
+        $result = $this->client->deleteIssue('df439ff0-a8ed-4972-aada-956fb0bb27ce');
         $this->assertSame('df439ff0-a8ed-4972-aada-956fb0bb27ce', $result);
     }
 
@@ -1410,8 +1403,7 @@ public function testDeleteLanguage(): void
             ]
         ])));
 
-        $language = new Language();
-        $result = $this->client->deleteLanguage($language);
+        $result = $this->client->deleteLanguage('1584d8e2-b856-4519-a507-c2399af11af5');
         $this->assertSame('1584d8e2-b856-4519-a507-c2399af11af5', $result);
     }
 
@@ -1455,8 +1447,7 @@ public function testDeleteLocation(): void
             ]
         ])));
 
-        $location = new Location();
-        $result = $this->client->deleteLocation($location);
+        $result = $this->client->deleteLocation('c45e9a4a-80e1-46c2-8845-61bf4263255e');
         $this->assertSame('c45e9a4a-80e1-46c2-8845-61bf4263255e', $result);
     }
 
@@ -1500,8 +1491,7 @@ public function testDeletePrice(): void
             ]
         ])));
 
-        $price = new Price();
-        $result = $this->client->deletePrice($price);
+        $result = $this->client->deletePrice('38e96434-88a3-4f1c-9c39-b9160000c61a');
         $this->assertSame('38e96434-88a3-4f1c-9c39-b9160000c61a', $result);
     }
 
@@ -1545,8 +1535,7 @@ public function testDeletePublication(): void
             ]
         ])));
 
-        $publication = new Publication();
-        $result = $this->client->deletePublication($publication);
+        $result = $this->client->deletePublication('01fec4e9-fbff-4c2e-9752-a0562a506e4d');
         $this->assertSame('01fec4e9-fbff-4c2e-9752-a0562a506e4d', $result);
     }
 
@@ -1590,8 +1579,7 @@ public function testDeletePublisher(): void
             ]
         ])));
 
-        $publisher = new Publisher();
-        $result = $this->client->deletePublisher($publisher);
+        $result = $this->client->deletePublisher('a77ef552-856c-4585-9d35-fd58d2190b1b');
         $this->assertSame('a77ef552-856c-4585-9d35-fd58d2190b1b', $result);
     }
 
@@ -1635,8 +1623,7 @@ public function testDeleteReference(): void
             ]
         ])));
 
-        $reference = new Reference();
-        $result = $this->client->deleteReference($reference);
+        $result = $this->client->deleteReference('6b4060ff-a89b-4bdc-b722-2b87ef9d057a');
         $this->assertSame('6b4060ff-a89b-4bdc-b722-2b87ef9d057a', $result);
     }
 
@@ -1680,8 +1667,7 @@ public function testDeleteSeries(): void
             ]
         ])));
 
-        $series = new Series();
-        $result = $this->client->deleteSeries($series);
+        $result = $this->client->deleteSeries('dc4ed0f7-89a4-4760-aad3-adec7294706d');
         $this->assertSame('dc4ed0f7-89a4-4760-aad3-adec7294706d', $result);
     }
 
@@ -1725,8 +1711,7 @@ public function testDeleteSubject(): void
             ]
         ])));
 
-        $subject = new subject();
-        $result = $this->client->deleteSubject($subject);
+        $result = $this->client->deleteSubject('e7ab386e-186a-4b1c-aa6f-e974b8a1e3cd');
         $this->assertSame('e7ab386e-186a-4b1c-aa6f-e974b8a1e3cd', $result);
     }
 
@@ -1770,8 +1755,7 @@ public function testDeleteWork(): void
             ]
         ])));
 
-        $work = new Work();
-        $result = $this->client->deleteWork($work);
+        $result = $this->client->deleteWork('d81bab71-d9fe-456b-9951-2308b91db2b4');
         $this->assertSame('d81bab71-d9fe-456b-9951-2308b91db2b4', $result);
     }
 
@@ -1815,8 +1799,7 @@ public function testDeleteWorkRelation(): void
             ]
         ])));
 
-        $workRelation = new WorkRelation();
-        $result = $this->client->deleteWorkRelation($workRelation);
+        $result = $this->client->deleteWorkRelation('64019725-3e50-41de-a785-e4e5ddc4620a');
         $this->assertSame('64019725-3e50-41de-a785-e4e5ddc4620a', $result);
     }