THE FUNCTION OF THE REFERENCE LIBRARIAN is to conduct requests for knowledge to known or to possible sources. He can sometimes do this by turning with arm‐length familiarity to a bay full of familiar friends —B.N.B., Besterman, Walford, Britannica, Willings ‐ and an increasing number and variety of bibliographical aids to specialized fields in current literature, but a request for wide, intensive and retrospective book coverage of a subject can set him dancing for a whole afternoon.