My dad has a set of 1975 Britannica with the year book and also a set of Britannica Junior with the year books from 75,76 and 77. I was wondering if there was a market for these and what they are worth.

I didn't check eBay, but having worked in libraries for years and seeing patrons bring in old encyclopedia sets to donate or sell in our book sale, I'd say the value is probably very low. The sets are out of date, and most people today find what they need on the Internet, not in print material.

If you'd get $25 a set, you'd be doing well. Just in case I'm wrong, call your library's reference department and ask about this. They will have a collectible/rare books source to consult.