Poels, Vefie / de Valk, Hans: Cardinal Willem van Rossum, Benedict XV, and the Centralization of the Pontifical Missionary Works in Rome (1918–22), in: Melloni, Alberto / Cavagnini, Giovanni / Grossi, Giulia (eds.): Benedict XV: A Pope in the World of the 'Useless Slaughter' (1914-1918), Turnhout, Belgium 01/2020 Brepols Publishers, pp. 575-589.