A well-known twosome puts authors of The Mystery Writers of America through their paces in stories of collaborations -- between detectives, father and son, cop and pathologist, -- the Holmes-Watson technique. Names: Blochman, Boucher, Oursler, Palmer, Halliday, Queen, Walsh, Patrick, Gilbert, MacDonald, Simenon, Allingham, Treat and others; plenty of places and gimmicks and tricks; all sleekly slick. Proved.