Complex sentence: Subsequently, the theories and methods originated by Lowenfeld became the basis of a range of therapeutic techniques, in particular the development of sandplay therapy credited to Dora M. Kalff, a Swiss Jungian analyst, who studied with Dr Lowenfeld.
Split into simpler sentences: Subsequently, the theories and methods originated by Lowenfeld became the basis of a range of therapeutic techniques. In particular the development of sandplay therapy by Dora M. Kalff, a Swiss therapist who studied with Dr Lowenfeld.