On the problem of Schleswig the best collection is the _Manual historique de la question du Slesvig_, ed. F. de Jessen (Copenhagen, 1906); supplemented by _Le Slesvig du Nord, 1906-1914_ (Copenhagen, 1915). For a German view, see E. Daenell, _Das Dänentum in Nordschleswig seit 1864_ (Kiel, 1913). After the armistice Daenell protested strongly against the surrender of any part of Schleswig to Denmark: _Has Denmark a claim to North Sleswick?_ (Münster, 1918). For a summary of conditions under Prussian rule, see L. M. Larson, in _American Historical Review_, xxiv, pp. 227-252 (1919); and M. Mackeprang, _Nordslesvig_ (Copenhagen, 1910; German translation, 1912). For the Danish discussion in 1919, see Miss Karen Larsen, in _Political Science Quarterly_, December, 1919. G. Rosendal’s _Sönderjylland_ (Odense, [1919]) contains convenient maps and statistics. See also the British _Handbook_. * * * * * For the history of Belgium, the standard work of H. Pirenne has not advanced beyond 1648; there are brief sketches by L. van der Essen (Chicago, 1916) and L. Vander Linden (Paris, 1918). General economic conditions are described by W. Bürklin, _Handbuch des belgischen Wirtschaftslebens_ (Göttingen and Berlin, 1916); and by Gehrig and Wäntig, _Belgiens Volkswirtschaft_ (Leipzig, 1918). An admirable special study of Belgian commerce will be found in A. Demangeon, “Le port d’Anvers,” in _Annales de géographie_, 1918, pp. 307-339, elaborated in the second volume of the _Travaux du Comité d’Etudes_. For Belgium’s coal and mineral resources, see P. Krusch, _Die nutzbaren Lagerstätten Belgiens_ (Essen, 1916). The British Handbook on _Belgium_ (1920) is particularly convenient, as are the related pamphlets in the same series. German plans for permanent control of Belgium are illustrated in S. Grumbach, _Das annexionistische Deutschland_ (Lausanne, 1917; abbreviated translation, New York, 1917); and in Notestein and Stoll, _Conquest and Kultur_ (Washington, 1918). A specimen of this vast literature of annexation may be seen in the work of a Bonn professor: E. Zitelmann, _Das Schicksal Belgiens beim Friedensschluss_ (third edition, Munich, 1917), where the systematic subjection of Belgium is planned. The exploitation of the Flemish question by the Germans is described by F. Passelecq, _La question flamande et l’Allemagne_ (Paris and Nancy, 1917).