Mo Wuji was worried that someone detect his spiritual will, so as he walked, he would occasionally stop to flip through some manuals. Here, a manual which was not being exchanged would have a thin string attached to it, preventing it from being taken away. Even a quick browse would only allow the first few pages to be seen. The later pages have all been sealed.
So with this process of walking and stopping, Mo Wuji encountered quite a number of cultivation manuals with "Immortal" in the name. However, Mo Wuji could only smile ruefully when he noticed that this "Immortal" manuals were largely Human Grade manuals. They weren't like the Immortal Mortal Technique which had a eye-catching name.
At the start, Mo Wuji wasn't really anxious. With all the Five Great Empire sects’ manuals concentrated here, coupled with the fact that the Immortal Mortal Technique was so common, it should be easy to find the sequel to the Immortal Mortal Technique.