Ramachandran, R. (August 1991). ""AR1991.pdf""(PDF). The Institute of Mathematical Sciences. Archived(PDF) from the original on 23 April 2024. Retrieved 23 April 2024.
Ramachandran, R. (August 1991). ""AR1991.pdf""(PDF). The Institute of Mathematical Sciences. Archived(PDF) from the original on 23 April 2024. Retrieved 23 April 2024.