Ballantine and Virgin Books bios on them last week, Carol Publishing Group publisher Steven Schragis closed the deal on a book written by British group The Spice Girls themselves. To be accompanied by 100 color "personal photographs," the 100-page paperback, Girl Power!, will be published by Citadel Press with a 50,000-75,000 first printing and will coincide with the Girls' appearance on "Saturday Night Live" on April 12. The book is a project of British-based book packager Cat Ledger, and the Girls are self-publishing the book in the U.K. with a 100,000 first printing. But will young female fans turn out to buy a book about and/or by female singers as strongly as they do for such male idols as New Kids on the Block et. al? Stay tuned.