Science feature article: Illustrations by Elliott Dold, Jr. Appeared in the collected works [i]The Best of L. Sprague de Camp[/i], published in 1978, reissued in 1986; and [i]Years in the making: The Time-Travel Stories of L. Sprague de Camp[/i], published in 2005. Appeared in the anthologies [i]Coming Attractions[/i], edited by Martin Greenberg, published in 1957; and [i]The Analog Anthology #1[/i], edited by Stanley Schmidt, published in 1980, reissued in 1981 under the title [i]Analog's Golden Anniversary Anthology[/i] and 1982 under the title [i]Fifty Years of the Best Science Fiction From Analog[/i].