Vintage Martin Info
Excellent site with extensive information about vintage Martin guitars.

The Ultimate Martin Guitar Forum. A great web forum with large membership of knowledgeable Martin guitar enthusiasts.

The Unofficial Martin Database
An ambitioius project to catalog the model and any additional info about each of the first 100,000 serialized Martin Guitars.

C.F. Martin & Co
C.F. Martin and Company's official website.

Martin 2-17 Page
Another informative page on the Martin 2-17.