 Into the 19th century, the Christians of Istanbul tended to be either Greek Orthodox, members of the Armenian Apostolic Church or Catholic Levantines.Eldem Edhem, in his entry on "Istanbul" in the "Encyclopedia of the Ottoman Empire", wrote that about 50% of the residents of the city were Muslim at the turn of the 20th Century.In the late Ottoman period non-Muslim ethnic minorities in the empire used French as a lingua franca and therefore used French-language newspapers and other media.