"Seed To Seed" is probably
the best book on the subject of saving vegetable seeds.
It does give good information regarding safe isolation distances, and techniques.
It is a seed saver's book, NOT a gardening book, though it does give regional information, based on input from successful seed savers from various (US) regions.
I would not consider seed saving without having a copy on hand. An essential tool for seed savers (IMHO).
With corn, if you have the space, (and a long
enough growing season), a good alternative is to use varieties with widely spaced pollination times. An extra early variety
should not interfere with a late variety.
I know a grower who specializes in peppers. The plants that he reserves for seed saving are isolated in screened cages away from the eating plants. This takes him more time, as he needs to time the opening/closing periods so that the pollinators can
get in when they are needed, but not be allowed to visit other varieties of seed plants.
See attached table for guidelines on pepper varieties: