Lehmhus, J., and C. G. Gustavsson. “Hybrids Between Bar-Headed Goose Anser Indicus and Snow Goose Anser Caerulescens”. Ornis Svecica, vol. 24, no. 3–4, Oct. 2014, pp. 147–163, doi:10.34080/os.v24.22556.