Porcelli & Delgado https://pmc.ncbi.nlm.nih.gov/articles/PMC5201132/

Palmer et al. https://www.apa.org/pubs/journals/releases/bul-bul0000410.pdf

WHO PFA https://iris.who.int/bitstreams/e7e129fb-b306-496d-84a5-67bb70abc130/download