Sankar, P. V., and E. V. Krishnamurthy. “ALWIN - Algorithmic Chemical Notation System for Organic Compounds. Part III: Fused and Spiro Ring Systems.1 (Non-Conveationai Methods in Document Retrieval. 18)”. Journal of Information and Knowledge, vol. 9, no. 4, Dec. 1972, pp. 554-7, doi:10.17821/srels/1972/v9i4/49266.