Complex sentence: He wrote a book on the Slovene impressionist painter Rihard Jakopič and maintained a close friendship with the painter Ivan Grohar, the illustrators Riko Debenjak and Miha Maleš, and the sculptor Jakob Savinšek.
Split into simpler sentences: He wrote a book on the Slovene impressionist painter Rihard Jakopič. The and maintained a close friendship with the painter Ivan Grohar, illustrators Riko Debenjak and Miha Maleš and with the sculptor Jakob Savinšek.