On 25 May 1085 Pope Gregory VII died in exile. The ninth centenary of the death of this great pope – ‘the greatest who has ever sat in St. Peter's chair’ Erich Caspar called him in 1924 – provides an obvious pretext for a bibliographical essay. What makes such. an essay a necessary exercise rather than a mere commemorative gesture is the fact that there is not available at present in any language a full-scale biography of Hildebrand–Gregory which reflects the current state of research. There is no doubt that Gregorian studies are flourishing: the colloquium in Salerno in May 1985 will offer an impressive account of research in progress. Over 200 books and articles on different aspects of the life and thought of Hildebrand-Gregory, written in the second half of this century, are listed below. Perhaps it is this sheer wealth of material and opinion which has disheartened potential biographers. The following survey concentrates on Gregorian literature since 1947, the year in which the Salesian and Scriptor of the Vatican Library, Father Giovanni Battista Borino (1881–1966) founded in Rome the journal Studi Gregoriani, which has certainly fulfilled its founder's purpose of stimulating research into the history of the papal reform movement.