Online catalogue https://pacific.st-andrews.ac.uk/ [search at random, e.g. "Justinian". Click on link "See this record in context": you then get the entire catalogue. So done 2014 June 12]
Concordance between original MSS numbers (in sequence from no. 1 onward) and shelfmarks attributed under the Library of Congress shelfmark system. This is a drawer of file cards. Only the first 700 numbers of MSS are continuously covered. Thereafter the card file becomes more and more lacunous [Fully checked].