Motorbooks.com - http://www.motorbooks.com Topics include automotive, aircraft, tractors, and bicycles.
RepairManual.com - http://www.repairmanual.com How to carry out routine maintenance, restoration and servicing of cars motorcycles, and boats.
Technical Publications Service - http://www.tractormanuals.co.uk Suppliers of manuals for tractors, engines, ATVs, and other maintenance and collectors books on tractors and machinery.
NADAguides.com - https://www.nadaguides.com/BuyTradeGuides.asp?wSec=8&wPg=1464 Price appraisal guides for used automobiles, classic vehicles, boats, airplanes, motorcycles, snowmobiles and recreational vehicles.
Nene Valley Railway Books - http://www.nenevalley-railwaybooks.co.uk/ Transport related publications, both new and secondhand including shipping, railways, canals, aviation, and buses.