Complex sentence: In 1969, he began working at the Sonia Shankman Orthogenic School; following the retirement of Bruno Bettelheim in 1973, Cohler became director of the school.
Split into simpler sentences: In 1969, he began working at the Sonia Shankman Orthogenic School. Following the retirement of Bruno Bettelheim in 1973, Cohler became director of the school.