diff --git a/docs/en/Tutorials/Part-1.md b/docs/en/Tutorials/Part-1.md
index 20b64f3189..1711c21e25 100644
--- a/docs/en/Tutorials/Part-1.md
+++ b/docs/en/Tutorials/Part-1.md
@@ -982,11 +982,13 @@ import { GetBooks } from '../actions/books.actions';
 import { Books } from '../models/books';
 import { BooksService } from '../../books/shared/books.service';
 import { tap } from 'rxjs/operators';
+import { Injectable } from '@angular/core';
 
 @State<Books.State>({
   name: 'BooksState',
   defaults: { books: {} } as Books.State,
 })
+@Injectable()
 export class BooksState {
   @Selector()
   static getBooks(state: Books.State) {
diff --git a/docs/en/Tutorials/Part-2.md b/docs/en/Tutorials/Part-2.md
index 08e17e0e3f..8bf3cb053b 100644
--- a/docs/en/Tutorials/Part-2.md
+++ b/docs/en/Tutorials/Part-2.md
@@ -574,11 +574,13 @@ import { GetBooks, CreateUpdateBook } from '../actions/books.actions'; //<== add
 import { Books } from '../models/books';
 import { BooksService } from '../../books/shared/books.service';
 import { tap } from 'rxjs/operators';
+import { Injectable } from '@angular/core';
 
 @State<Books.State>({
   name: 'BooksState',
   defaults: { books: {} } as Books.State,
 })
+@Injectable()
 export class BooksState {
   @Selector()
   static getBooks(state: Books.State) {
@@ -1330,11 +1332,13 @@ import { GetBooks, CreateUpdateBook, DeleteBook } from '../actions/books.actions
 import { Books } from '../models/books';
 import { BooksService } from '../../books/shared/books.service';
 import { tap } from 'rxjs/operators';
+import { Injectable } from '@angular/core';
 
 @State<Books.State>({
   name: 'BooksState',
   defaults: { books: {} } as Books.State,
 })
+@Injectable()
 export class BooksState {
   @Selector()
   static getBooks(state: Books.State) {
diff --git a/docs/pt-BR/Tutorials/Angular/Part-I.md b/docs/pt-BR/Tutorials/Angular/Part-I.md
index 05e8a1b7e1..7fbe0827ce 100644
--- a/docs/pt-BR/Tutorials/Angular/Part-I.md
+++ b/docs/pt-BR/Tutorials/Angular/Part-I.md
@@ -537,11 +537,13 @@ import { GetBooks } from '../actions/books.actions';
 import { Books } from '../models/books';
 import { BooksService } from '../../books/shared/books.service';
 import { tap } from 'rxjs/operators';
+import { Injectable } from '@angular/core';
 
 @State<Books.State>({
   name: 'BooksState',
   defaults: { books: {} } as Books.State,
 })
+@Injectable()
 export class BooksState {
   @Selector()
   static getBooks(state: Books.State) {
diff --git a/samples/BookStore-Angular-MongoDb/angular/src/app/store/states/books.state.ts b/samples/BookStore-Angular-MongoDb/angular/src/app/store/states/books.state.ts
index f2d1c78d90..54ecaeb155 100644
--- a/samples/BookStore-Angular-MongoDb/angular/src/app/store/states/books.state.ts
+++ b/samples/BookStore-Angular-MongoDb/angular/src/app/store/states/books.state.ts
@@ -7,11 +7,13 @@ import {
 import { Books } from "../models/books";
 import { BooksService } from "../../books/shared/books.service";
 import { tap } from "rxjs/operators";
+import { Injectable } from '@angular/core';
 
 @State<Books.State>({
   name: "BooksState",
   defaults: { books: {} } as Books.State
 })
+@Injectable()
 export class BooksState {
   @Selector()
   static getBooks(state: Books.State) {