Rishi had already requested the books from the library. It did cost him money, but Rishi valued his time more. He received the order in the evening; Rishi checked and discovered two books. These two books cost him all his contribution points; he could have ordered just the skill book and saved a lot of money.
Rishi pondered it for a long time after carefully considering all options. He had to use more credits to buy guidebooks, but the benefit was that these books contained a simplified way to master the skill and the insights of someone who had mastered these skills. It also saved him a lot of time that he would have needed to understand the skill books on his own.
The first was a black-and-white book titled 'How to Master Stealth Skill.' It was a book written specifically for an assassin who had mastered the advanced level of stealth. In this book, he discusses how anyone can learn to be stealthy.