1. Determination of the heliocentric cosmic ray density gradient using neutron monitor data;Bercovitch;Proc. Int. Conf. Cosmic Rays 11th,1969
2. The heliocentric radial density gradient of relativistic cosmic rays in 1967–68;Bercovitch;Proc. Int. Conf. Cosmic Rays 12th,1971
3. Solar cycle variation of cosmic-ray north-south anisotropy and radial gradient;Bieber;Astrophys. J.,1986
4. Couzens, D. A., , J. H., King, , Interplanetary Medium Data Book, suppl. 3A, 1977–1985, National Space Science Data Center, NASA, Greenbelt, Md., 1986,
5. Relationship between sector boundaries and polar nucleonic intensity variations: The heliocentric gradient during solar cycle 20;Duggal;Proc. Int. Conf. Cosmic Rays 15th,1977