1986, Plasma beta endorphin in man during partial immersion in water using the therapeutic method

Digiesi V, Baldi E, Scartabelli P, Masi F, Spillantini MG, Cerchiai G

Minerva Med. 1986 Feb 28;77(7-8):209-13

https://www.ncbi.nlm.nih.gov/pubmed/3005917