diff --git a/dmp-frontend/src/app/ui/reference/reference-field/editor/reference-dialog-editor.component.html b/dmp-frontend/src/app/ui/reference/reference-field/editor/reference-dialog-editor.component.html
index 6365667ae..373ceaa0f 100644
--- a/dmp-frontend/src/app/ui/reference/reference-field/editor/reference-dialog-editor.component.html
+++ b/dmp-frontend/src/app/ui/reference/reference-field/editor/reference-dialog-editor.component.html
@@ -12,8 +12,14 @@
 			<div class="col">
 				<mat-form-field class="w-100">
 					<mat-label>{{field}}</mat-label>
-					<input matInput type="text" [name]="field" [formControl]="formGroup.get(field)" required>
+					<input matInput type="text" [name]="field" [formControl]="formGroup.get(field)">
 					<mat-error *ngIf="formGroup.get(field).hasError('required')">{{'GENERAL.VALIDATION.REQUIRED' | translate}}</mat-error>
+					<ng-container *ngIf="field == systemFields[0]">
+						<i matSuffix class="fa fa-spinner fa-spin" *ngIf="formGroup.get(field).pending && !referenceExists"></i>
+						<mat-icon *ngIf="!formGroup.get(field).pending && formGroup.get(field).dirty && formGroup.get(field).valid && !referenceExists" class="text-success" matSuffix>check</mat-icon>
+						<mat-icon *ngIf="!formGroup.get(field).pending && formGroup.get(field).dirty && formGroup.get(field).invalid || referenceExists" class="text-danger" matSuffix>clear</mat-icon>
+						<small *ngIf="referenceExists" class="text-danger">{{'REFERENCE-FIELD.REFERENCE-DIALOG-EDITOR.IDENTIFIER-EXISTS' | translate}}</small>
+					</ng-container>
 				</mat-form-field>
 			</div>
 		</div>
@@ -22,17 +28,16 @@
 				<div class="col">
 					<mat-form-field class="w-100">
 						<mat-label>{{field.label}}</mat-label>
-						<input matInput type="text" [name]="field.code" [formControl]="formGroup.get(field.code)" required>
+						<input matInput type="text" [name]="field.code" [formControl]="formGroup.get(field.code)">
 						<mat-error *ngIf="formGroup.get(field.code).hasError('required')">{{'GENERAL.VALIDATION.REQUIRED' | translate}}</mat-error>
 					</mat-form-field>
 				</div>
 			</div>
 		</ng-container>
 		
-		{{formGroup.value | json}}
 	</div>
 	<div mat-dialog-actions class="row">
 		<div class="ml-auto col-auto"><button mat-raised-button type="button" mat-dialog-close>Cancel</button></div>
-		<div class="col-auto"><button mat-button color="primary" [disabled]="!formGroup.valid" (click)="send()" type="button">Save</button></div>
+		<div class="col-auto"><button mat-button color="primary" [disabled]="!isFormValid" (click)="send()" type="button">Save</button></div>
 	</div>
 </form>
diff --git a/dmp-frontend/src/app/ui/reference/reference-field/editor/reference-dialog-editor.component.ts b/dmp-frontend/src/app/ui/reference/reference-field/editor/reference-dialog-editor.component.ts
index ced2a056b..c7298a3df 100644
--- a/dmp-frontend/src/app/ui/reference/reference-field/editor/reference-dialog-editor.component.ts
+++ b/dmp-frontend/src/app/ui/reference/reference-field/editor/reference-dialog-editor.component.ts
@@ -19,6 +19,13 @@ export class ReferenceDialogEditorComponent extends BaseComponent implements OnI
 	referenceType: ReferenceType;
 	systemFields: string[];
 	label: string = null
+	private existingReferences: string[] = [];
+
+	get referenceExists(){
+		const reference  = this.formGroup.get(this.systemFields[0]).value;
+		
+		return this.existingReferences.find((r)=>r === reference)
+	}
 
 	constructor(
 		private referenceTypeService: ReferenceTypeService,
@@ -29,6 +36,7 @@ export class ReferenceDialogEditorComponent extends BaseComponent implements OnI
 	) { 
 		super(); 
 		this.label = data.label;
+		this.existingReferences = data.existingReferences;
 		this.formGroup = this.fb.group({});
 	}
 
@@ -59,6 +67,10 @@ export class ReferenceDialogEditorComponent extends BaseComponent implements OnI
 
 	}
 
+	isFormValid() {
+		return this.formGroup.valid && !this.referenceExists;
+	}
+
 	send() {
 		this.formService.touchAllFormFields(this.formGroup);
 		if (!this.formGroup.valid) { return; }
diff --git a/dmp-frontend/src/app/ui/reference/reference-field/reference-field.component.ts b/dmp-frontend/src/app/ui/reference/reference-field/reference-field.component.ts
index 99957ce50..c01fde684 100644
--- a/dmp-frontend/src/app/ui/reference/reference-field/reference-field.component.ts
+++ b/dmp-frontend/src/app/ui/reference/reference-field/reference-field.component.ts
@@ -9,7 +9,10 @@ import { SingleAutoCompleteConfiguration } from '@app/library/auto-complete/sing
 import { BaseComponent } from '@common/base/base.component';
 import { takeUntil } from 'rxjs/operators';
 import { ReferenceDialogEditorComponent } from './editor/reference-dialog-editor.component';
-import { ReferencePersist } from '@app/core/model/reference/reference';
+import { Reference, ReferencePersist } from '@app/core/model/reference/reference';
+import { ReferenceSearchLookup } from '@app/core/query/reference-search.lookup';
+import { Guid } from '@common/types/guid';
+import { nameof } from 'ts-simple-nameof';
 
 @Component({
 	selector: 'app-reference-field-component',
@@ -44,25 +47,43 @@ export class ReferenceFieldComponent extends BaseComponent implements OnInit {
 	}
 
 	addReference() {
-		const dialogRef = this.dialog.open(ReferenceDialogEditorComponent, {
-			width: '500px',
-			restoreFocus: false,
-			data: {
-				referenceTypeId: this.referenceType.id,
-				label: this.label ?? this.referenceType.name
-			},
-		});
-		dialogRef.afterClosed()
-			.pipe(takeUntil(this._destroyed))
-			.subscribe(newResult => {
-				if (!newResult) { return; }
-				// const dataRepositoryModel = new ExternalDataRepositoryEditorModel(result.id, result.name, result.abbreviation, result.uri, result.pid, result.source);
-				// (<UntypedFormArray>this.formGroup.get('dataRepositories')).push(dataRepositoryModel.buildForm());
 
-				let results = this.form.value as ReferencePersist[];
-				if (results == undefined) results = [];
-				results.push(newResult);
-				this.form.setValue(results);
-			});
+		this.referenceService.searchWithDefinition(this.buildAutocompleteSearchLookup(this.referenceType.id))
+		.pipe(takeUntil(this._destroyed))
+		.subscribe(
+			references => {
+				const dialogRef = this.dialog.open(ReferenceDialogEditorComponent, {
+					width: '500px',
+					restoreFocus: false,
+					data: {
+						referenceTypeId: this.referenceType.id,
+						label: this.label ?? this.referenceType.name,
+						existingReferences: references.map(x => x.reference)
+					},
+				});
+				dialogRef.afterClosed()
+					.pipe(takeUntil(this._destroyed))
+					.subscribe(newResult => {
+						if (!newResult) { return; }		
+						let results = this.form.value as ReferencePersist[];
+						if (results == undefined) results = [];
+						results.push(newResult);
+						this.form.setValue(results);
+					});
+			}
+		);
+	}
+
+	private buildAutocompleteSearchLookup(typeId: Guid): ReferenceSearchLookup {
+		const lookup: ReferenceSearchLookup = new ReferenceSearchLookup();
+		lookup.page = { size: 100, offset: 0 };
+		lookup.project = {
+			fields: [
+				nameof<Reference>(x => x.reference),
+			]
+		};
+		lookup.typeId = typeId;
+		lookup.order = { items: [nameof<Reference>(x => x.label)] };
+		return lookup;
 	}
 }
diff --git a/dmp-frontend/src/assets/i18n/en.json b/dmp-frontend/src/assets/i18n/en.json
index 6cc4950c9..4b310778a 100644
--- a/dmp-frontend/src/assets/i18n/en.json
+++ b/dmp-frontend/src/assets/i18n/en.json
@@ -1354,7 +1354,8 @@
 			"INSERT-MANUALLY": "Insert it manually"
 		},
 		"REFERENCE-DIALOG-EDITOR": {
-			"TITLE": "Add a"
+			"TITLE": "Add a",
+			"IDENTIFIER-EXISTS": "Reference Identifier Exists!"
 		}
 	},
 	"DMP-CLONE-DIALOG": {