Ladder edition
Lancer books
A ladder edition
by Elizabeth Hough Sechrist and Janette Woolsey ; adapted by Gloria Stashower
Lancer Books c1966 Lancer book L-17 , Ladder edition
Available at 1 libraries
by Isaac Asimov ; adapted by Robert M. Walker
Lancer Books c1966 Lancer book L-19 , Ladder edition
by Bern Dibner
Lancer Books c1966 Ladder edition
Available at 2 libraries