Complex sentence: Much of the scholarly work on ǀXam was performed by Wilhelm Bleek, a German linguist of the 19th century, who studied a variety of ǀXam spoken at Achterveld, and (with Lucy Lloyd) another spoken at Strandberg and Katkop.
Split into simpler sentences: Much of the scholarly work on the ǀXam language was performed by Wilhelm Bleek, a German linguist of the 19th century. He had studied a variety of ǀXam spoken at Achterveld, and (with Lucy Lloyd) another spoken at Strandberg and Katkop.