Internet sources on getting better at Endgames

I. On what to do to get better?

1. >4 Steps to Endgame Mastery< on chess.com by NM SmarterChess Matt Jensen
2. more to follow

II. Lessons

III. Endgame positions

1. >Chess Endgame Studies and Compositions< on Facebook led by co-founders GM Max Illingworth and IM Cyrus Lakdawala
2. >Play Endgames positions against the computer< on 365chess
3. more to follow