共 6 条
[1]
Cartan E., 1932, Ann. Scuola Norm. Super. Pisa Cl. Sci., V1, P333
[2]
Cartan E., 1933, Ann. Math. Pura Appl., V11, P17
[6]
Penrose R., 1977, Reports on Mathematical Physics, V12, P65, DOI 10.1016/0034-4877(77)90047-7