Michels, Franziska, Claudia Schilling, Franziska Rausch, Sarah Eifler, Mathias Zink, Andreas Meyer-Lindenberg, and Michael Schredl. 2014. “Nightmare Frequency in Schizophrenic Patients, Healthy Relatives of Schizophrenic Patients, Patients at High Risk States for Psychosis, and Healthy Controls”. International Journal of Dream Research 7 (1):9-13. https://doi.org/10.11588/ijodr.2014.1.11819.