diff --git a/appengine/datastore/app.js b/appengine/datastore/app.js
index 0113597725..4c28d110d4 100644
--- a/appengine/datastore/app.js
+++ b/appengine/datastore/app.js
@@ -25,8 +25,8 @@ app.enable('trust proxy');
 
 // By default, the client will authenticate using the service account file
 // specified by the GOOGLE_APPLICATION_CREDENTIALS environment variable and use
-// the project specified by the GCLOUD_PROJECT environment variable. See
-// https://googlecloudplatform.github.io/gcloud-node/#/docs/google-cloud/latest/guides/authentication
+// the project specified by the GOOGLE_CLOUD_PROJECT environment variable. See
+// https://github.com/GoogleCloudPlatform/google-cloud-node/blob/master/docs/authentication.md
 // These environment variables are set automatically on Google App Engine
 const Datastore = require('@google-cloud/datastore');
 
diff --git a/appengine/pubsub/app.js b/appengine/pubsub/app.js
index 777e68fca8..1d7ea87ba4 100644
--- a/appengine/pubsub/app.js
+++ b/appengine/pubsub/app.js
@@ -25,7 +25,7 @@ const process = require('process'); // Required for mocking environment variable
 // By default, the client will authenticate using the service account file
 // specified by the GOOGLE_APPLICATION_CREDENTIALS environment variable and use
 // the project specified by the GOOGLE_CLOUD_PROJECT environment variable. See
-// https://github.com/GoogleCloudPlatform/google-cloud-node/blob/master/docs/authentication
+// https://github.com/GoogleCloudPlatform/google-cloud-node/blob/master/docs/authentication.md
 // These environment variables are set automatically on Google App Engine
 const PubSub = require('@google-cloud/pubsub');
 
diff --git a/appengine/storage/app.js b/appengine/storage/app.js
index ce98948a65..20be9f2668 100644
--- a/appengine/storage/app.js
+++ b/appengine/storage/app.js
@@ -25,8 +25,8 @@ const bodyParser = require('body-parser');
 
 // By default, the client will authenticate using the service account file
 // specified by the GOOGLE_APPLICATION_CREDENTIALS environment variable and use
-// the project specified by the GCLOUD_PROJECT environment variable. See
-// https://googlecloudplatform.github.io/gcloud-node/#/docs/google-cloud/latest/guides/authentication
+// the project specified by the GOOGLE_CLOUD_PROJECT environment variable. See
+// https://github.com/GoogleCloudPlatform/google-cloud-node/blob/master/docs/authentication.md
 // These environment variables are set automatically on Google App Engine
 const Storage = require('@google-cloud/storage');