Thanks, Chris ... Yes, there was a series of twelve novels by Dane Hartman based on the "Dirty Harry" character. They had nothing to do with any of the "Dirty Harry" films.
There was also a novelization of the original screenplay of
Dirty Harry, by Phillip Rock. That is, the novelization is by Rock ... the screenplay was by Harry Julian Fink and R.M. Fink (and Dean Riesner). And there were novelizations of the next three "Dirty Harry" screenplays as well (but not
The Dead Pool, for some reason).
You can read more about all these books
here. They all do turn up on e-Bay regularly, or you might try searching
http://www.bookfinder.com . Good luck!