Peter Pütz

Brain electrical activity and subjective experience during altered states of consciousness: ganzfeld and hypnagogic states.

Dietrich Lehmann, D. Lehmann, Peter Pütz, 2002, International journal of psychophysiology : official journal of the International Organization of Psychophysiology.

EEG correlates of multimodal ganzfeld induced hallucinatory imagery.

Jirí Wackermann, Matthias Braeunig, J. Wackermann, 2006, International journal of psychophysiology : official journal of the International Organization of Psychophysiology.

Psychobiology of altered states of consciousness.

Dietrich Lehmann, Niels Birbaumer, Thomas Weiss, 2013, Psychological bulletin.