NISAS-2000 - die „Nationwide Insomnia Screening and Awareness Study”. - Wittchen,H.U.; Krause,P.; Höfler,M.; Winter,S.; Spiegel,B.; Hajak,G.; Riemann,D.; Pittrow,D.; Steiger,A.; Pfister,H. (Nervenheilkunde, 2001)