Here's why terms matter: The one everybody calls copper is actually bronze. The one that's mostly zinc (inside) is coated with copper, even though people don't call it copper. Confused? That's what imprecise terminology causes.
The one everyone calls copper is actually brass, not bronze. Bronze has to contain tin, and the U. S. cent stopped containing tin in 1963. Copper and zinc is brass.
And I know you will probably agree that's it's sad no one buys the books anymore. It's in the Red Book, Numismatic News and Coin World. Oh well..