Takai N, Yamaguchi M, Aragaki T, Eto K, Uchihashi K, Nishikawa Y. Effect of psychological stress on the salivary cortisol and amylase levels in healthy young adults. Arch Oral Biol. 2004 Dec;49(12):963–8. doi: 10.1016/j.archoralbio.2004.06.007. PMID: 15485637.