In addition the original Hardy Boys series and the The Hardy Boy Casefiles, Joe and Frank have appeared in Nancy Drew/Hardy Boys crossover "supermysteries". I hated these as a child, because they were far too Nancy Drew centered and she always ended up solving the crime while the Hardy Boys just sat around and got saved by Nancy. I guess there was some message being sent about female empowerment or something, I don't know. Nonetheless, I read them because the Hardy Boys were my heros. Plus, I wanted to see Nancy and Frank hookup. There was a lot of sexual tension going on, but it never happened. God, I hated those books.