One of the best sources for the world of European Renaissance Humanism in the early sixteenth century is the correspondence of Erasmus. Among those with whom he exchanged letters are:
Editions
P. S. Allen, ed. Opus epistolarum Des. Erasmi Roterodami, 12 vols (Oxford, 1906–1958) (in Latin)
Collected Works of Erasmus (Toronto, 1976-), based on the Allen edition, with a small number of additions and emendations (in English)