OBNB doesn't sell books, but you may be able to find a copy at one of these websites:
Moscow variation : 1 P-K4 P-QB4 2 N-KB3 p-Q3 3 B-N5+ by L. M. Pickett. ISBN 0900928859. Published by The Chess Player in 1976. Publication and catalogue information, links to buy online and reader comments.