Tolong jelaskan mengenai Sumber sekunder dari Jordanus

Henry Yule's Cathay, giving a version of the Epistles, with a commentary, &c. (Hakluyt Society, 1866) pp. 184–185, 192-196, 225-230

F. Kunstmann, Die Mission in Meliapor und Tana und die Mission in Columbo in the Historisch-politische Blätter of Phillips and Görres, xxxvii. 2538, 135-152 (Munich, 1856), &c.