Sankar, P. V., and E. V. Krishnamurthy. “ALWIN - Algorithmic Chemical Notation System for Organic Compounds. Part IV: Bridged Rings and Ring of Rings (Non-Conventional Methods in Document Retrieval. 19)”. Journal of Information and Knowledge, vol. 9, no. 4, Dec. 1972, pp. 575-84, doi:10.17821/srels/1972/v9i4/49268.