Vitaly Chekhover (also spelled Tschechower or Czechower, pronounced "chekh a VYAIR") (Russian: Виталий Чеховер) (1908-1965) was a Soviet chess player and chess composer. He was also a pianist.
In the beginning of his career as an endgame study composer, Chekhover often revised traditional studies of other authors. He strove to bring them into a more sparse and economical form, often with fewer pieces – hence focusing on the actual problem itself, rather than the position on the board. Later he found his own style and composed a number of original, independent chess studies and problems. Starting 1936, Chekhover published more than 160 endgame studies. He is considered a prominent specialist on knight endgames, and has written several books on the subject; either alone, or with coauthors such as Russian grandmaster Yuri Averbakh.
Between 1947 and 1965 he participated in the Soviet Union championship for chess composition. Chekhover twice received the title Master of Sports of the USSR. In 1956 he was awarded the title International Judge of Chess Compositions by FIDE, and received the FIDE title International Master of Chess Compositions in 1961. SOURCE: http://en.wikipedia.org/wiki/Vitaly_Chekhover
Click on "solution" and "move list" to see alternate lines and comments (even if you already solved the puzzle on your own). Generally the most difficult defensive line is the solution with alternatives shown in the move list - alternatives generally lose in fewer moves.