If I ever found myself in the position, that I could have but a single reference book covering elasmobranch teeth, Cappetta's Chondrichthyes II would be the immediate choice. It might not give me the ability to hang a specific name on any tooth, but it would likely get me to a family or genus for nearly every tooth. The more I learn about selachian/batoid teeth, the greater my respect for the author, appreciation of the illustrations and reliance on the text.,

Volume 3A: Chondrichthyes I
Paleozoic Elasmobranchii
Rainer Zangerl - 1981

Handbook of Paleoichthyology has been re printed. For Zangerl (Euro 70) or Cappetta (Euro 100) see: Verlag Dr. Friedrich Pfeil.