Library 1, Library 2, Library 3, Level 3, N (Introduction to Natural Science), O (Mathematical Science and Chemistry), T (Industrial Technology), P (Astronomy), Q (Biological Science), TB (General Industry), TD (Oil and Gas), TF (Metallurgical Industry). TL (Atomic Energy Industry), R (Medicine, Health), X (Environment), S (Agricultural Science), Z (Comprehensive), TM (Electrician), TN (Electronic), TP (Computer), TQ (Chemical Industry), TS (Light Industry, Handicraft Industry) and TU (Architecture) Japanese books are divided into five categories.