This hefty coffee-table book documents, for the first time, the seminal private art collection of Munich's Herbert and Annette Kopp. The title Permanent Trouble functions as a synonym for the permanent outsider; the Kopps acquired works by Hansjorg Dobliar, Paul McCarthy, and Gert and Uwe Tobias, among others, when those artists were still outsiders. Those ''youngsters'' contrast with the Kopp's works by an older generation, such as Sylvie Fleury, Gunther Forg, Mike Kelley and Martin Kippenberger. Anyone who follows the European avant-garde will be fascinated by the evolution and breadth of this unique collection. (John Waters's hilarious ''Visit Marfa'' poster alone is a good enough reason to buy the book.) A gorgeous tribute to collectors with a splendid eye.