Main repository
Book: Kotlin 官网参考.pdf kotlin-reference.pdf
Link&Download: https://www.kotlincn.net/docs/reference/
Branch: dev-kotref
Book: kotlin-for-android-developers 中文版.pdf (kotlin-for-android-developers-zh.pdf)
Download: https://pan.baidu.com/s/1ulo8pSbnh-G67WbZM0rSDQ
Branch: dev-k4ad
Book: kotlin实战.pdf (kotlin-in-action.pdf)
Download: https://pan.baidu.com/s/1qcdRj3zJkX9AXkVLOfx7Vg
Branch: dev-kotlin