diff --git a/lib/ontologies_api_client/models/agent.rb b/lib/ontologies_api_client/models/agent.rb
new file mode 100644
index 0000000..f16da4c
--- /dev/null
+++ b/lib/ontologies_api_client/models/agent.rb
@@ -0,0 +1,14 @@
+require_relative "../base"
+
+module LinkedData
+  module Client
+    module Models
+      class Agent < LinkedData::Client::Base
+        include LinkedData::Client::Collection
+        include LinkedData::Client::ReadWrite
+
+        @media_type = "http://xmlns.com/foaf/0.1/Agent"
+      end
+    end
+  end
+end
diff --git a/lib/ontologies_api_client/models/category.rb b/lib/ontologies_api_client/models/category.rb
index 0f41b59..7df0645 100644
--- a/lib/ontologies_api_client/models/category.rb
+++ b/lib/ontologies_api_client/models/category.rb
@@ -5,6 +5,8 @@ module Client
     module Models
       class Category < LinkedData::Client::Base
         include LinkedData::Client::Collection
+        include LinkedData::Client::ReadWrite
+
         @media_type = "http://data.bioontology.org/metadata/Category"
       end
     end
diff --git a/lib/ontologies_api_client/models/group.rb b/lib/ontologies_api_client/models/group.rb
index 803b148..3061d72 100644
--- a/lib/ontologies_api_client/models/group.rb
+++ b/lib/ontologies_api_client/models/group.rb
@@ -5,6 +5,8 @@ module Client
     module Models
       class Group < LinkedData::Client::Base
         include LinkedData::Client::Collection
+        include LinkedData::Client::ReadWrite
+
         @media_type = "http://data.bioontology.org/metadata/Group"
       end
     end
diff --git a/lib/ontologies_api_client/models/identifier.rb b/lib/ontologies_api_client/models/identifier.rb
new file mode 100644
index 0000000..4261de3
--- /dev/null
+++ b/lib/ontologies_api_client/models/identifier.rb
@@ -0,0 +1,14 @@
+require_relative "../base"
+
+module LinkedData
+  module Client
+    module Models
+      class Identifier < LinkedData::Client::Base
+        include LinkedData::Client::Collection
+        include LinkedData::Client::ReadWrite
+
+        @media_type = "http://www.w3.org/ns/adms#Identifier"
+      end
+    end
+  end
+end