This was published possibly published a second time, as I've seen it reported with both $0.50 and $0.75 cover prices.
Other resources
(None on file)
Acknowledgements: Robert Silverberg for cause, support, and cooperation; Ken Seamon for graphics; Rodney Walters for books and info; Alvaro Zinos-Amaro for comments and content; and all the fellow fans who have sent encouragement, information, and translations.