To learn analog circuits, you must read about the new concept analog circuits" Northwest Analog Electronics Teacher Yang Jianguo's these series of books replies can be found in the extraction code.

"New Concept Analog Circuit"
-Transistor Link: https://pan.baidu.com/s/1dIIy1L3qS0qT0Rt9O0TOEA
Extraction code: 28tl

"New Concept Analog Circuit 2-Negative Feedback and Operational Amplifier Fundamentals"

Link: https://pan.baidu.com/s/1L9_ddGauDv4fl_Cg_9NBeQ
extraction code: w45w

New Concept Analog Circuit 3-Source Circuit-Signal Source and Power Supply
Link: https://pan.baidu.com/s/1W0zlLyjjpJHJyezVLxxb7A
Extraction code: k68i

New Concept Analog
Circuit_Book IV_Signal Processing Circuit Link: https://pan.baidu.com/s/1XclrXRkNJpSY8Uze9ikyKg
Extraction code: xjpb

New concept analog circuit-frequency characteristics and filter of op amp circuit
Link: https://pan.baidu.com/s/1ALBczwHuczx5zhbch3zVIA
extraction code: oujp