Robert Nisbet Bain, 1911 Encyclopædia Britannica, Volume 3… (1911)
“ It was in Bela’s reign that the emperor Frederick I., in the spring of 1189, traversed Hungary with 100,000 crusaders, on which occasion the country was so well policed that no harm was done to it and the inhabitants profited largely from their commerce with the German host. In his last years Bela assisted the Greek emperor Isaac II. Angelus against the Bulgarians. His first wife bore Bela two sons, Emerich and Andrew. On her death he married Margaret of France, sister of King Philip Augustus. ”
