Schadow, C., M. Schredl, J. Rieger, and A. S. Göritz. “The Relationship Between Lucid Dream Frequency and Sleep Quality: Two Cross-Sectional Studies”. International Journal of Dream Research, vol. 11, no. 2, Nov. 2018, pp. 154-9, doi:10.11588/ijodr.2018.2.48341.