Complex sentence: Jan Dylik had an enormous influence in the development of periglacial geomorphology as he in addition to his role in the Periglacial Comission and "Biuletyn Peryglacjalny" he had extensive contacts among Eastern Block scientists such as Konstantin K. Markov and A. I. Popov.
Split into simpler sentences: Jan Dylik had an enormous influence in the development of periglacial geomorphology as he in addition to his role in the Periglacial Comission and "Biuletyn Peryglacjalny" he had extensive contacts among Eastern Block scientists. In particular Jan Dylik had regular contact with Soviet scientists such as Konstantin K. Markov and A. I. Popov.