↑ Kluver, H. 1966 Mescal and mechanisms and hallucinations University of Chicago Press. p. 70
↑ Christer Fuglesang, Livio Narici, Piergiorgio Picozza, Walter G Sannita(2006).“Phosphenes in low earth orbit: survey responses from 59 astronauts”.Aviat Space Environ Med77(4): 449-52.