Reboreda JC, Fernandez GJ (1997). "Sexual, seasonal and group size differences in the allocation of time between vigilance and feeding in the greater rhea, Rhea americana". Ethology. 103 (3): 198–207. Bibcode:1997Ethol.103..198R. doi:10.1111/j.1439-0310.1997.tb00116.x.
Reboreda JC, Fernandez GJ (1997). "Sexual, seasonal and group size differences in the allocation of time between vigilance and feeding in the greater rhea, Rhea americana". Ethology. 103 (3): 198–207. Bibcode:1997Ethol.103..198R. doi:10.1111/j.1439-0310.1997.tb00116.x.