study of trade-routes, Wilhelm Heyd, _Geschichte des Levantehandels im Mittelalter_, 2 vols. (1879), with a French trans. (1885-1886), and Aloys Schulte, _Geschichte des mittelalterlichen Handels und Verkehrs zwischen Westdeutschland und Italien_, 2 vols. (1900). GENERAL TREATMENTS OF EXPLORATION AND COLONIZATION. _Cambridge Modern History_, Vol. I (1902), ch. i, ii; A. G. Keller, _Colonization: a Study of the Founding of New Societies_ (1908), a textbook, omitting reference to English and French colonization; H. C. Morris, _History of Colonization_, 2 vols. (1908), a useful general text; M. B. Synge, _A Book of Discovery: the History of the World's Exploration, from the Earliest Times to the Finding of the South Pole_ (1912); _Histoire générale_, Vol. IV, ch. xxii, xxiii, and Vol. V, ch. xxii; S. Ruge, _Geschichte des Zeitalters der Entdeckungen_ (1881), in the ambitious Oncken Series; Paul Leroy-Beaulieu, _La colonisation chez les peuples modernes_, 6th ed., 2 vols. (1908), the best general work in French; Charles de Lannoy and Hermann van der Linden, _Histoire de l'expansion coloniale des peuples européens_, an important undertaking of two Belgian professors, of which two volumes have appeared--Vol. I, _Portugal et Espagne_ (1907), and Vol. II, _Néerlande et Danemark, 17e et 18e siècle_ (1911); Alfred Zimmermann, _Die europaischen Kolonien_, the main German treatise, in 5 vols. (1896-1903), dealing with Spain and Portugal (Vol. I), Great Britain (Vols. II, III), France (Vol. IV), and Holland (Vol. V). Much illustrative source-material is available in the publications of the Hakluyt Society, Old Series, 100 vols. (1847-1898), and New Series, 35 vols. (1899-1914), selections having been separately published by E. J. Payne (1893-1900) and by C. R. Beazley (1907). An account of the medieval travels of Marco Polo is published conveniently in the "Everyman" Series, and the best edition of the medieval travel-tales which have passed under the name of Sir John Maundeville is that of The Macmillan Company (1900). For exploration prior to Columbus and Da Gama, see C. R. Beazley, _The Dawn of Modern Geography_, 3 vols. (1897-1906).