PREGALACTIC HELIUM ABUNDANCE AND ABUNDANCE GRADIENTS ACROSS OUR GALAXY FROM PLANETARYNEBULAE - SABBADIN, F; PEIMBERT, M; DODORICO, S (UNIV NACL AUTONOMA MEXICO,INST ASTRON,MEXICO CITY,MEXICO, 1976)
ASTROPHYS J
Keywords: PRE GALACTIC, HELIUM, ABUNDANCE, ABUNDANCE, GRADIENTS, ACROSS, GALAXY, PLANETARY NEBULAE; ASTRONOMIA Y ASTROFISICA; COSMOLOGIA Y COSMOGONIA; GALAXIAS