w3school

http://www.runoob.com/w3cnote_genre/android

https://www.tutorialspoint.com/android/android_sqlite_database.htm

http://www.w3school.com.cn/

https://www.journaldev.com/10439/android-butterknife-example

https://code.tutsplus.com/tutorials/quick-tip-using-butter-knife-to-inject-views-on-android--cms-23542