@bootblackCub Wikipedia linked to this 1992 study: http://onlinelibrary.wiley.com/store/10.1111/j.1365-2869.1992.tb00019.x/asset/j.1365-2869.1992.tb00019.x.pdf?v=1&t=jckgzvpw&s=14617a8f74541b6db175691508765071c1fa1042
(Although I'm not sure if it's good/universally accessible because I'm still half asleep on my phone)