Space: a call for action : proceedings of the 10th annual international space development conference, May 22-27, 1991, San Antonio, Texas / edited by Robert C. Blackledge, Carol Luckhardt Redfield, Steven B. Seida . San Diego :  Univelt Inc. , 1991 . xvii, 385 s . ISBN 0-912183-05-5 . [1, of that borrowed 0]