diff --git a/src/index.ts b/src/index.ts
index 3c190c0..50f5547 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -4,10 +4,10 @@ import passport from 'passport';
 import authRoutes from './authentication/routes';
 import { connectToDatabaseServer } from './db-utils';
 import sendGridMail from '@sendgrid/mail';
-import { userProfileRoutes } from './user-profile/routes';
+import { userProfileRoutes } from './user-profile/profile-routes';
 import { categoryRoutes } from './user-profile/category-routes';
 import { shelfRoutes } from './user-profile/shelf-routes';
-import { wordRoutes } from './user-profile/word-routes';
+import { libraryRoutes } from './library/library-routes';
 
 const SENDGRID_API_KEY = process.env.SENDGRID_API_KEY || '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';
 
@@ -22,7 +22,7 @@ app.use('/auth/', authRoutes);
 app.use('/user/', userProfileRoutes);
 app.use('/category/', categoryRoutes);
 app.use('/shelf/', shelfRoutes);
-app.use('/library/', wordRoutes);
+app.use('/library/', libraryRoutes);
 
 app.get('/', (request, response) => {
     response.send('Server running @ port' + app.get('port'));
diff --git a/src/user-profile/word-routes.ts b/src/library/library-routes.ts
similarity index 86%
rename from src/user-profile/word-routes.ts
rename to src/library/library-routes.ts
index 79d735a..88f3b60 100644
--- a/src/user-profile/word-routes.ts
+++ b/src/library/library-routes.ts
@@ -3,13 +3,13 @@ import passport from 'passport';
 import { DB_NAME, getDatabaseClient } from '../db-utils';
 import { Word } from '../models/word';
 
-export const wordRoutes = express.Router();
+export const libraryRoutes = express.Router();
 
 export const jwtAuthentication = passport.authenticate('jwt', { session: false });
 
 // Get All Words
 
-wordRoutes.get('/all/', jwtAuthentication, async (request, response) => {
+libraryRoutes.get('/all/', jwtAuthentication, async (request, response) => {
     const wordCollection = getDatabaseClient().db(DB_NAME).collection<Word>('words');
 
     const allWords = await wordCollection.find().toArray();
@@ -20,7 +20,7 @@ wordRoutes.get('/all/', jwtAuthentication, async (request, response) => {
     return;
 });
 
-wordRoutes.get('/search/', jwtAuthentication, async (request, response) => {
+libraryRoutes.get('/search/', jwtAuthentication, async (request, response) => {
     const wordCollection = getDatabaseClient().db(DB_NAME).collection<Word>('words');
 
     if (!request.body.name) {
@@ -39,7 +39,7 @@ wordRoutes.get('/search/', jwtAuthentication, async (request, response) => {
     return;
 });
 
-wordRoutes.post('/add/', jwtAuthentication, async (request, response) => {
+libraryRoutes.post('/add/', jwtAuthentication, async (request, response) => {
     const wordCollection = getDatabaseClient().db(DB_NAME).collection<Word>('words');
 
     if (!request.body.name || request.body.grammaticalDetails) {
diff --git a/src/models/shelf.ts b/src/models/shelf.ts
index c34567a..a1e6866 100644
--- a/src/models/shelf.ts
+++ b/src/models/shelf.ts
@@ -16,7 +16,7 @@ interface AddedWord {
     isArchived: boolean,
 }
 
-export interface Shelf {
+interface Shelf {
     name: string,
     description?: string,
     viewType: viewPermissionType,
@@ -24,7 +24,7 @@ export interface Shelf {
     addedWords?: Array<AddedWord>
 }
 
-interface MongoAddedWord extends Omit<AddedWord, "word"> {
+export interface MongoAddedWord extends Omit<AddedWord, "word"> {
     word: string,
 }
 
diff --git a/src/user-profile/routes.ts b/src/user-profile/profile-routes.ts
similarity index 100%
rename from src/user-profile/routes.ts
rename to src/user-profile/profile-routes.ts
diff --git a/src/user-profile/shelf-routes.ts b/src/user-profile/shelf-routes.ts
index 14c0239..fe7a448 100644
--- a/src/user-profile/shelf-routes.ts
+++ b/src/user-profile/shelf-routes.ts
@@ -1,10 +1,11 @@
-import { ObjectId } from 'bson';
+import { ObjectID, ObjectId } from 'bson';
 import express from 'express';
 import passport from 'passport';
 import { MongoCategory } from '../models/category';
 import { DB_NAME } from '../db-utils';
 import { getDatabaseClient } from '../db-utils';
-import { MongoShelf } from '../models/shelf';
+import { MongoAddedWord, MongoShelf } from '../models/shelf';
+import { Word } from '../models/word';
 
 export const shelfRoutes = express.Router();
 
@@ -97,6 +98,8 @@ shelfRoutes.post('/add/', jwtAuthentication, async (request, response) => {
 // Update shelf
 shelfRoutes.put('/update/', jwtAuthentication, async (request, response) => {
     const shelfCollection = getDatabaseClient().db(DB_NAME).collection<MongoShelf>('shelves');
+    const wordCollection = getDatabaseClient().db(DB_NAME).collection<Word>('words');
+    const updatedAddedWords: Array<MongoAddedWord> = request.body.addedWords ? request.body.addedWords : [];
 
     const currentShelf = await shelfCollection.findOne({
         _id: new ObjectId(request.body._id)
@@ -115,6 +118,29 @@ shelfRoutes.put('/update/', jwtAuthentication, async (request, response) => {
         }
     }
 
+    
+    for (let i = 0; i < updatedAddedWords.length; i += 1) {
+        if (!updatedAddedWords[i].word || !updatedAddedWords[i].isArchived || 
+            !updatedAddedWords[i].isFavourite || !updatedAddedWords[i].nextRevisionDateTime || 
+            !updatedAddedWords[i].notes || !updatedAddedWords[i].revisionHistory || !updatedAddedWords[i].spaceBetweenRecall) {
+                response.status(400);
+                response.send("Missing key in " + JSON.stringify(updatedAddedWords[i]));
+                return;
+        }
+
+        const wordId = updatedAddedWords[i].word;
+        
+        const matchedWord = await wordCollection.findOne({
+            _id: new ObjectId(wordId)
+        });
+
+        if (!matchedWord) {
+            response.status(400);
+            response.send("Word with ID " + updatedAddedWords[i] + " is not present in the library" );
+            return;
+        }
+    }
+
     try {
         await shelfCollection.updateOne({
             _id: new ObjectId(request.body._id),
@@ -122,6 +148,7 @@ shelfRoutes.put('/update/', jwtAuthentication, async (request, response) => {
             $set: {
                 name: request.body.name ? request.body.name : currentShelf.name,
                 description: request.body.description ? request.body.description : currentShelf.description,
+                addedWords: updatedAddedWords,
                 isArchived: request.body.isArchived !== undefined ? request.body.isArchived : currentShelf.isArchived
             }
         });