See Biblissima, See Bannister, H. M. Monumenti vaticani di paleografia musicale latina ID# 63[ ff.2r, 6v 12th C German neumes]. The riddles on ff.49v-52r are titled in a Caesarean cypher, see Finch, C. E. (1967). "Codex Vat. Barb. Lat. 721 as a Source for the Riddles of Symphosius". Transactions and Proceedings of the American Philological Association, 98, 173–179. DOI