Sorted, by author...

• Bresee, Frank & Bobb Lynes
  Radio's Golden Years: A Visual Guide to the Shows & Stars
  It uses the informational cartoon, a format popularized in Ripley's Believe It or Not. Each of the 254 panels (8.5" by 11") deals with a single show or radio-related topic. There is informative text about each show, and drawings of radio people actors, producers, directors, writers, announcers, composers and even products. Bobb did the drawings, hundreds of them. Not just detectives are covered, but there are a lot of them in this book: Big Town, Boston Blackie, Bulldog Drummond, Casey - Crime Photographer, Dick Tracy, Ellery Queen, Fat Man, Green Hornet, Johnny Dollar six of the eight Johnny Dollars), Let George Do It, Michael Shayne, Mr. and Mrs. North, Mr. Chameleon, Mr. Keen - Tracer of Lost Persons, Nero Wolfe, Nick Carter, Night Beat, Pat Novak For Hire, Perry Mason, Philip Marlowe, Richard Diamond, Rocky Fortune, Sam Spade, Sgt. Preston, The Shadow, Sherlock Holmes, Tales of the Texas Rangers, and The Thin Man.
  This self-published, limited-edition (1,000 copies) softback book, is available from the authors & costs $25.00 (US) postpaid. Send your orders to Radio's Golden Years, c/o Bobb Lynes, Box 561, So. Pasadena, CA 91031."
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• Buxton, Frank and Owen Bill
  The Big Broadcast 1920-1950
  Scarecrow Press, Second Edition, 1996.
  "The Big Broadcast" lists network and syndicated radio shows that ran between the 1920's to 1950's - "the golden age of radio". A good source for cast lists and articles on genres, sound effects and "independent" networks. Minimal descriptions of most shows. A good OTR reference book.
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• Dunning, John.
  On The Air: The Encyclopedia of Old-Time Radio
  New York : Oxford University Press, 1997.
  This book is considered the New Testament of OTR reference books; John's 1976 Tune In Yesterday (see below) is the Old Testament. On The Air is more than just a revision of his earlier book. There are some 1,500 radio shows presented in alphabetical order. There is extensive information on each show's length of run, cast, writers, and directors. There is also an extensive bibliography.
  What really sets this book part is John's books is his insightful writing about the shows; he writes from the heart and with passion. John is an acknowledged expert on OTR; he had OTR shows on various stations in Denver, CO for over 20 years. John is also a best-selling author - his two novels on, cop-turned rare book seller/detective, Cliff Janeway are very readable. If I could only buy one OTR book, this one is it.
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• Dunning, John.
  Tune In Yesterday
  Prentice-Hall, 1976.
  703 pages; 32 pages of pictures in hardback edition. unfortunately, out-of-print. Copies of this book have sold recently for as much as $300.00. This was before John's new OTR book came out. Less comprehensive than John's new book and without the extensive information on each show's length of run, cast, writers, and directors, but still the best book on OTR of its time. Really a great read and reference tool. I recently added this book to my collection and feel lucky to get it.
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• French, Jack,
  Private Eyelashes...Buy this book
  Boalsburg, PA: BearManor Media, 2004.
  A contributor to this site, old time radio historian Jack French presents his opus to radio lady crimefighters! From the thrilling days of yesteryear, he dishes up the dirt on such lady gumshoes as Irene Delroy, Phyl Coe, Carolyn Day, Kitty Keene and Candy Matson.
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• Grams, Martin,
  Radio Drama A Comprehensive Chronicle of American Network Programs, 1932–1962
  Jefferson, NC: McFarland, 2000
  Includes more than 300 program logs (many appearing in print for the first time) drawn from newspapers, script files in broadcast museums, records from NBC, ABC and CBS, and the personal records of series directors. Each entry contains a short broadcast history that includes directors, writers, and actors, and the broadcast dates and air times. Some series logs include cast lists for each episode. A comprehensive index rounds out the work. Included are logs for favorite radio detective series such as Casey - Crime Photographer (AKA Flashgun Casey, Crime Photographer), The Adventures of Frank Race, The Adventures of Nero Wolfe, The Adventures of Philip Marlowe, The Adventures of Sam Spade, Paladin, I Love a Mystery, I Love Adventure, Nick Carter and others.
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• Grams, Martin,
  The Radio Adventures of Sam Spade....Buy this book
  OTR Publishing, 2007
  All you ever wanted to know about the immensely popular radio show starring Howard Duff: the good, the bad and the blacklist. The success of the show upped the ante on Hammett's already popular creation, and the book delves into the subsequent comics strips, magazine articles and radio cross-overs and imitations, including bios on the principal players, a complete episode guide, an unproduced radio scrip and t is reprinted, and a reprint of "Babe Lincoln," a female detective that never came to be. Grams is the author of numerous books on old-time radio and old-time television, including he staggering Radio Drama A Comprehensive Chronicle of American Network Programs, 1932–1962.
  
  
• Hickerson, Jay.
  The New, Revised Ultimate History of Network Radio Program and Guide To All Circulating Shows
  Self-published by author
  Jay's book is an indispensable research tool for me. It fills in the blanks that Dunning doesn't cover. Provided for each of the 6,000 shows is: title, dates of run, genre, network, stars, and number and dates of available shows. Jay regularly provides updates at minimal cost. A strong number 2 on my OTR must-have list. For ordering info, contact the author at Box 4321, Hamden, CT 06514.
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• Sies, Luther F.,
  Encyclopedia of American Radio, 1920–1960
  Jefferson, NC: McFarland, 2000
  Got a big Christmas budget and serious old-time radio collector on your list? Get them an OTR Encyclopedia! Comprising nearly 29,000 entries, this massive volume comprehensively covers the performers and programming on American radio from its inception to its golden age. The real fan will find lots of long-sought after information about favorite detective series and actors. The encyclopedia includes entries for programs, announcers, orchestras, musicians, vocalists, comedians, vocal groups, readers, whistlers, musical saw soloists, ministers, sports commentators, reviewers (of books, plays and movies), celebrities, and other personnel broadcasting over American radio from the 1920s to the 1960s. Additional entries cover commercial radio, educational broadcasting, firsts in radio history, opera on radio, religious broadcasting, sports broadcasting, women in radio, border radio, children's programs, comedy on radio, crime shows and mysteries, daytime dramatic serials, and disk jockeys, among other topics.

Thanks to our OTR expert Stewart Wright for these suggestions, and the commentary...