1. Sokhey J, Kim Farley RJ, Bhargava I. Case definitions in the surveillance of vaccine preventable diseases.Indian Pediatr 1988; 25: 599–609.
2. Damok I, Magrath DI. Guide to poliovirus isolation and serological techniques for poliomyelitis surveillance.WHO Offset Publication No. 46, Geneva: 1979; 9–11
3. Rhodes AJ, Vanrooyen CE.Text Book of Virology, 5th ed. Baltimore: The Williams & Wilkins Co. 1968; 541–568.
4. Girst NR, Bell EJ, Follett EHC et al.Diagnostic Methods in Clinical Virology, 3rd ed. Oxford: Blackwell Scientific Publications, 1979; 129–141.
5. Lennett EH.Diagnostic Procedures for Viral and Rickettsial Infections, 4th ed. New York: American Public Health Association. Inc. 1969: 529–595.