Tri-Diurnal Variation in Cosmic Ray Intensity on Quiet Days during Solar Cycles 21-22 Kumar, S. ; Richharia, M. K. ; Chauhan, M. L. ; Gulati, U. ; Khare, D. K. ; Shrivastava, S. K. Abstract Publication: International Cosmic Ray Conference Pub Date: 1995 Bibcode: 1995ICRC....4..623K