In addition to the named special collections of books acquired from a single source and kept together, there are many purchased or donated items in the general special collections. Former owners of significant quantities of such books include George Grote, the London Institution, and Frederick Stroud Read. Other books scattered among the general collections whcih in the past have occasionally been listed among special collections are the Cohen Collection, the George Collection of Piano Music, the Mrs Humphrey Ward Collection and the Plainsong and Mediaeval Music Society Library.