Complex sentence: In 1958 he left "Sztandar Młodych" and started working for the Polish Press Agency and soon after also joined the weekly "Polityka" (where he worked till 1962).
Split into simpler sentences: In 1958 he left "Sztandar Młodych" and started working for the Polish Press Agency. Shortly afterwards he also joined the weekly "Polityka" (where he worked till 1962).