1. P.A. Wisocki et al. The global distribution of avian eggshell colours suggest a thermoregulatory benefit of darker pigmentation. Nature Ecology & Evolution. Published online October 28, 2019. doi: 10.1038/s41559-019-1003-2.

2.https://www.theguardian.com/science/2019/oct/28/scientists-crack-mystery-of-bird-eggs-colour-variation

3.https://www.sciencenews.org/article/bird-eggs-laid-cold-climates-are-darker-may-keep-eggs-warm

4.https://www.medicaldaily.com/reason-bird-eggs-color-variation-cracked-scientists-445032

5. Lee JW & Yoo JC (2004) Effect of host egg color dimorphism on interactions between the vinous-throated parrotbill (Paradoxornis webbianus) and common cuckoo (Cuculus canorus). Korean Journal of Biological Sciences 8(2):77-80.