I want to know the answer to the following question:
What writer joined Jonassohn in the study of the whole of human history?
All the background I'm provided with is that "For example, Frank Chalk and Kurt Jonassohn studied the whole of human history, while Leo Kuper and R. J. Rummel in their more recent works concentrated on the 20th century, and Helen Fein, Barbara Harff and Ted Gurr have looked at post World War II events.". Is that enough to answer the question?
Answer: yes