Originally posted by HomerJSimpson
Where did you find these books?
They're both published by Dover in the United States, however, both may be out of print by now, but sometimes they turn up on eBay.
The Troitski book was truncated from a German edition of 500 problems. Later, the English translation included a special section on the theory of two knights vs. a pawn. The Dover edition does not include this section. Capablanca said there was great value to be had from the study of Troitski's book.
The Roycroft book was previously published in hardback/descriptive notation as, "Test-Tube Chess."
Other desirable Dover books on endgame studies and tactics are: “Tactics of the Endgame,” by Jeno Ban and “1,234 Modern Endgame Studies,” by Sutherland.