Johri, V. B.; Kalligas, D.; Singh, G. P.; Everitt, C. W. F. (March 1995). "Gravitational energy in the expanding universe". General Relativity and Gravitation. 27 (3): 313–318. Bibcode:1995GReGr..27..313J. doi:10.1007/BF02109127. S2CID120110466.
Johri, V. B.; Kalligas, D.; Singh, G. P.; Everitt, C. W. F. (March 1995). "Gravitational energy in the expanding universe". General Relativity and Gravitation. 27 (3): 313–318. Bibcode:1995GReGr..27..313J. doi:10.1007/BF02109127. S2CID120110466.
Johri, V. B.; Kalligas, D.; Singh, G. P.; Everitt, C. W. F. (March 1995). "Gravitational energy in the expanding universe". General Relativity and Gravitation. 27 (3): 313–318. Bibcode:1995GReGr..27..313J. doi:10.1007/BF02109127. S2CID120110466.