Complex sentence: Johannes Winkler (1874-1958), a Dutch doctor who was sent to Toba in 1901 and learned the pustaha from a datu named Ama Batuholing Lumbangaol, created a comprehensive study on the content of pustaha.
Split into simpler sentences: Johannes Winkler (1874-1958), a Dutch doctor who was sent to Toba in 1901 and learned the pustaha from a datu named Ama Batuholing Lumbangaol. He created a comprehensive study on the content of pustaha.