Studio Astrology Series
Publisher: Viking Press
Related Series: Studio Handbooks
A bit of a stretch, in that none of the 12 titles are numbered in a traditional way. I'm including this series because you can make a loose series number out of the calendar dates that correspond to the astrological sign and their ISBNs are in sequence (see the Aug. 31, 1970, PW ad).
Ad, PW, June 15, 1970, at 6:
The Studio Astrology Series
Each of these twelve handsomely illustrated paperbacks--one for each sign of the Zodiac--is revised and adapted from chapters in the popular Coffee Table Book of Astrology. Inexpensive, beautifully packaged, they are perfect all-occasion gifts that people will buy for personal use as well. The counter-display pre-pack contains 144 books, 12 copies of each 12 titles.
October 670-02021-4 $0.95 each
Ad, PW, Aug. 31, 1970, at 182 (indicating release date for all 12 titles is Oct. 13, 1970, and listing all titles with SBNs).