Checkmate in Two Puzzles Test (Very Hard) - Chess.com
Difficult Chess Puzzles for Advanced Players
Hardest Checkmate in Two Puzzle??? 7# - YouTube
Unbelievably hard puzzle! (rating 3000+, white to move)! - Chess Forums - Chess.com
10 Hardest Mate In 1 Chess Puzzles That'll Make Your Head Spin – Maroon Chess
G. T. Karber on Twitter: "I love this chess puzzle that Paul Morphy composed when he was 10. See if you can find mate in 2 for white. https://t.co/4Kg1qoVe0K" / Twitter