Janz, Lisa; Elston, Robert G.; Burr, George S. (18 May 2009). "Dating North Asian surface assemblages with ostrich eggshell: implications for palaeoecology and extirpation". Journal of Archaeological Science. 36 (9): 1982–1989. Bibcode:2009JArSc..36.1982J. doi:10.1016/j.jas.2009.05.012.
Janz, Lisa; Elston, Robert G.; Burr, George S. (18 May 2009). "Dating North Asian surface assemblages with ostrich eggshell: implications for palaeoecology and extirpation". Journal of Archaeological Science. 36 (9): 1982–1989. Bibcode:2009JArSc..36.1982J. doi:10.1016/j.jas.2009.05.012.