Here are some great hobby reference books as follows -- Note these can be shipped book rate to save money -- actual postage additional (your choice of priority or book rate).

McDougald's "History and Guide to North American Pin Type Insulators" This out of print, 2 volume set, is absolutely one of the finest reference sources -- nice condition -- $50 for both

Elton Gish's "Multipart Porcelain Insulators (second edition)" -- By far the best reference on this subject! nice condition -- $20 (SOLD)

Marilyn Albers & N.R. Woodward's book "Glass Insulators from Outside North America" (second edition) -- An excellent guide to worldwide glass! Also has the Price guide which adds some additional CDs. -- both have a little water damage that does not affect the usability -- $20 for the set

Marilyn Albers & Jack Tod -- "Worldwide Porcelain Insulators" -- Nice shape - previous owner added some markings to the back -- $10 (SOLD)