Complex sentence: Already in 1921, he had presented two remarkable works, "Selbu" and "Tydal" and also published the controversial article "En nordisk Cro-Magnon type", which claimed that people in Tydal were descendants of the Cro Magnon.
Split into simpler sentences: Already in 1921 he had presented two remarkable works, "Selbu" and "Tydal". In 1921 he published the controversial article "En nordisk Cro-Magnon type", which claimed that people in Tydal were descendants of the Cro Magnon.