Book reviews: Markova remembers (Hamish Hamilton); The Royal Ballet, a picture history, rev. ed., by Kathrine Sorley Walker and Sarah C. Woodcock (Threshold); Balletmaster: a dancer's view of George Balanchine, by Moira Shearer (Sidgwick & Jackson); Antoinette Sibley: reflections of a ballerina, by Barbara Newman (Hutchinson); The Nutcracker, by David Walker (Moonstone Books)