구글 검색어: biorhythm https://en.wikipedia.org/wiki/Biorhythm 위키피디아 http://www.encyclopedia.com/science-and-technology/biology-and-genetics/biology-general/biorhythms 참고: 인간의 생체리듬 https://books.google.co.kr/books?id=XvbJ_dUlT0QC&pg=PA21&lpg=PA21&dq=how+many+years+have+you+been+living+for?++Biorhythm&source=bl&ots=KfbgkPGwmy&sig=wUrnzEqeow0aOWf0ZSzYSe6vp_E&hl=en&sa=X&ved=0ahUKEwjpuIX725PWAhVGOrwKHSxCCIwQ6AEISjAH#v=onepage&q=how%20many%20years%20have%20you%20been%20living%20for%3F%20%20Biorhythm&f=false 영문 안내서 소개 기타 http://www.procato.com/biorhythm/ https://www.bibliotecapleyades.net/bioritmos/ciencia_biorritmos03.htm http://webcache.googleusercontent.com/search?q=cache:lp4Y0SC_uXoJ:rpdp.net/admin/images/uploads/resource_11781.doc+&cd=7&hl=en&ct=clnk&gl=kr http://skepdic.com/biorhyth.html http://www.crystalinks.com/biorhythms.html http://www.care2.com/greenliving/biorhythm-theory-true-or-false-some-res...