Comedy fans: X-number of "basic" jokes?

Had to have been decades ago, but Steve Allen was on a show where the “basics of comedy” were being discussed, and he made it sound as if there were only seven basic jokes from which all others could be built.

I have searched the web many times for verification of that number, or any number, and have been left feeling that Steve was talking through his hat.

Have any of you: a) heard such a thing; b) seen any reliable source to deal with this issue; c) ever seen the “basic jokes”?

I’m not really asking for EXAMPLES by way of actual jokes. That could get messy!

If you know of a book or website that you consider authoritative, I’d like to know about it.

(is this the right forum for this question?)