Printing History
An Ace/Putnam Book.  Published by  G.P. Putnam's Sons.  Copyright © 1961, renewed 1989 by Virginia Heinlein.  Copyright © 1991 by Virginia Heinlein.  The price of the book was $24.95.

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I purchased this book as soon as it came out, so I don't know how many printings it went through before they discontinued the hardback.  Some science fiction book clubs may still sell a hardback of the 1991 version.  The cover's kind of plain, but I like it.