John and Carol McDougald. (1990). A History and Guide to North American Glass Pintype Insulators. Volume 1 and 2. Includes color pictures of insulators to help identify colors, history of insulator companies and supply houses, cross reference index from manufacturer and user embossing to CD number, a page of foreign glass, 2 pages on commemoratives with background information on them, a nice write-up on the CD 1038 Scott Cutter insulator, patent information, plus listings of known North American Glass Pintype insulators. 180 pages in volume 1, 325 pages in volume 2. Spiral bound. Very good shape. $40 postpaid in the U.S.