Heretik A, Simkovic M.
Cesk Psychiatr. 1993 Oct;89(5):300-5.
PMID: 8269525

Teusch L, Finke J, Luderer HJ, Speierer GW.
Psychother Psychosom Med Psychol. 2000 Jan;50(1):33-4.
PMID: 10686792

LEWIS ND.
Am J Psychother. 1961 Apr;15:184-92. doi: 10.1176/appi.psychotherapy.1961.15.2.184.
PMID: 13761748

THORNE FC.
J Consult Psychol. 1957 Dec;21(6):459-64. doi: 10.1037/h0045258.
PMID: 13481205

Kaplan CA.
Telemed Virtual Real. 1997 Oc;2(10):119.
PMID: 10174242