Drag and drop from one address book to another. You can of course select multiple Contacts using the usual shift and control click methods.

I use the Duplicate-contact-manager addon to sort out replicated contacts.

https://addons.mozilla.org/en-US/thunderbird/addon/duplicate-contact-manager/

How to install: http://xenos-email-notes.simplesite.com/416814616

Thanks for your reply, Xenos.

I didn't know about drag-and-drop for TB address books. I couldn't get it to work with moving an entire book.

However, your suggestion about the usual click methods did work: Click first contact/scroll to bottom/shift-click last contact/ then drag to target book moved then entire book. I did not anticipate that the operation would MOVE, NOT COPY the contacts. In other words, the source book was empty after the operation. I concede that MOVE not COPY is the customary action in most applications, so I should not have been surprised.

I will post separately another question that is related but not specific to this question.

Ctrl+click (and then drag) should make it a copy rather than a move. It's not well documented.