Leo Tolstoy | Pope Leo XIII | Leo Gorcey | Leo Burnett | Leo Brouwer | Leo VI the Wise | Leo | Pope Leo X | Leo Durocher | Wadada Leo Smith | Ted Leo | Pope Leo I | Pope Leo IX | Melissa Leo | Leo Carrillo | Ted Leo and the Pharmacists | Leo Castelli | Leo Burnett Worldwide | San Leo | Leo Strauss | Leo Marks | Leo Laporte | Léo Ferré | Leó Szilárd | Leo Slezak | Leo Frobenius | Leo Cárdenas | Pope Leo XII | Leonardo Leo | Leo Fall |
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.