Boxed Hardcover
Published September 1987
ISBN-13: 978-0-915368-90-7
ISBN-10: 0-915368-90-0
First edition, first printing of this book was September 1987
Other NESFA Press titles by Hal Clement
Music of Many Spheres 
Variations on a Theme by Sir Isaac Newton 
Trio for Slide Rule & Typewriter 
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