Complex sentence: Bonnier was president of Åhlen & Åkerlunds tidskriftsförlag 1957-1978 and 1980-1982 and then became chairman of the board of Bonniers Tidskriftsförlag.
Split into simpler sentences: Bonnier was president of Åhlen & Åkerlunds tidskriftsförlag 1957-1978 and 1980-1982. He then became chairman of the board of Bonniers Tidskriftsförlag.