Librantz, A. F. H.; Courrol, L. C.; Gomes, L.; Baldochi, S. L.; Ranieri, I. M. The Role of Nd3+ in the Population Inversion Between 1G4 and 3H6 States of Tm3+ in Yb:Nd:Tm:YLF Crystal. Exacta 2007, 5, 113-118.