Several books have been very helpful:
Patricia Baines Spinning Wheels, Spinners and Spinning (B.T. Batsford Ltd, London 1977) is a particularly useful survey of the different types of wheel, with clear illustrated explanations of their history and how they work.
David Bryant Wheels and Looms, Making equipment for spinning and weaving (BT Batsford Ltd,London 1987) contains expert accounts of how several traditional types of spinning wheel are made, complete with plans and instructions.
Judith Buxton Selected Canadian Spinning Wheels in Perspective, An Analytical Approach (Canadian Museum of Civilisation 1992; first published by National Museums of Canada 1980) is much more generally useful than the title implies. The accounts of exactly how different spinning devices work are technical but worth the effort to understand.
Eric Corran Understanding the Spinning Wheel (Melbourne 1997) is an interesting study of spinning wheels from the point of view of a successful maker.
Joan Whittaker Cummer A Book of Spinning Wheels (Peter E. Randall, New Hampshire USA 1994) has illustrations and descriptions of an astonishing variety of wheels from Europe and North America.
Heather Nicholson The Loving Stitch, A History of Knitting and Spinning in New Zealand (Auckland University Press, New Zealand 1998) has more about knitting than spinning but sheds useful light on the history of spinning in New Zealand.
David A. Pennington and Michael B. Taylor Spinning Wheels and Accessories (Schiffer Publishing Ltd, Pennsylvania USA 2004) is more in the nature of a catalogue for collectors of North American wheels, but there is a lot of interesting history and the colour illustrations are wonderful.