diff --git a/src/models/src/credential.ts b/src/models/src/credential.ts
index f171dfe..f325bf6 100644
--- a/src/models/src/credential.ts
+++ b/src/models/src/credential.ts
@@ -1,5 +1,6 @@
 import type { Base64String, ToJson, UUID } from '@/types.ts'
 import { Ressource } from '@models/ressource.ts'
+import type { Ref } from '@models'
 
 export class Credential<T extends CredentialCategory> extends Ressource {
 	static fromJSON<T extends CredentialCategory>(
@@ -69,6 +70,10 @@ export class Credential<T extends CredentialCategory> extends Ressource {
 	toString(): string {
 		return `Credential (${JSON.stringify(this)})`
 	}
+
+	toRef(): Ref<Credential<T>> {
+		return super.toRef() as Ref<Credential<T>>
+	}
 }
 
 export interface Credential<T extends CredentialCategory> extends Ressource {
diff --git a/src/models/src/group.ts b/src/models/src/group.ts
index 9acd75c..658cff9 100644
--- a/src/models/src/group.ts
+++ b/src/models/src/group.ts
@@ -106,6 +106,10 @@ export class Group extends Ressource {
 	toString(): string {
 		return `Group (${JSON.stringify(this)})`
 	}
+
+	toRef(): Ref<Group> {
+		return super.toRef() as Ref<Group>
+	}
 }
 
 export interface Group extends Ressource {
diff --git a/src/models/src/machine.ts b/src/models/src/machine.ts
index e72423c..7d4859c 100644
--- a/src/models/src/machine.ts
+++ b/src/models/src/machine.ts
@@ -93,6 +93,10 @@ export class Machine extends Ressource {
 	toString(): string {
 		return `Machine (${JSON.stringify(this)})`
 	}
+
+	toRef(): Ref<Machine> {
+		return super.toRef() as Ref<Machine>
+	}
 }
 
 export interface Machine extends Ressource {
diff --git a/src/models/src/service.ts b/src/models/src/service.ts
index b92c7ba..a9f9162 100644
--- a/src/models/src/service.ts
+++ b/src/models/src/service.ts
@@ -119,6 +119,10 @@ export class Service extends Ressource {
 	toString(): string {
 		return `Service (${JSON.stringify(this)})`
 	}
+
+	toRef(): Ref<Service> {
+		return super.toRef() as Ref<Service>
+	}
 }
 
 export interface Service extends Ressource {
diff --git a/src/models/src/user.ts b/src/models/src/user.ts
index f9ba41b..cfe9aab 100644
--- a/src/models/src/user.ts
+++ b/src/models/src/user.ts
@@ -168,6 +168,10 @@ export class User extends Ressource {
 	toString(): string {
 		return `User (${JSON.stringify(this)})`
 	}
+
+	toRef(): Ref<User> {
+		return super.toRef() as Ref<User>
+	}
 }
 
 export interface User extends Ressource {