When citing archives you need to provide enough information to allow a reader of your work to be able to locate and order the sources cited - the bare minimum is the name of the archive repository (e.g. Modern Records Centre, University of Warwick) and the document reference number, but it is good practice to provide more detailed information.
Our recommended format for citing archives held at the Modern Records Centre is as follows:
Short description of item, name of archive collection from which it comes, Modern Records Centre, University of Warwick, reference number.
Letter from Harold Macmillan to Richard Crossman, 15 December 1943; Richard Crossman Archive, Modern Records Centre, University of Warwick (MSS.154/3/AU/1/96)
'Women Against War and Fascism', bulletin no.3, Jan-Feb 1936; Maitland Sara Hallinan Collection, Modern Records Centre, University of Warwick (MSS.15X/1/319/1)