April 19- The Duchy of Limburg created in 1839 from parts of the Dutch Province of Limburg as a result of the Treaty of London and part of German Confederation.[4]
April 19- Britain, Prussia, France and the Netherlands agree to the Treaty of London that guaranteed the neutrality of Belgium.[5]: 417
^Die Leipzig-Dresdner Eisenbahn: Das Schienenverkehrsprojekt Deutsche Einheit Nr. 9 (in German). Dresden: Planungsgesellschaft Bahnbau Deutsche Einheit mbH. 1993. (12 page brochure)
^Jean-Louis Kupper (2007) Les origines du duché de Limbourg-sur-Vesdre", Revue belge de Philologie et d'Histoire Année 85-3-4 pp. 609-637 [1]
^Eric Van Hooydonk (2006). "Places of Refuge: The Belgian Experience". In Aldo E. Chircop; O. Lindén (eds.). Places of Refuge for Ships: Emerging Environmental Concerns of a Maritime Custom. Leiden: Martinus Nijhoff. pp. 415–428. ISBN9789004149526. Retrieved 30 May 2012.
^Dyson, C. C: The life of Marie Amélie last queen of the French, 1782-1866. With some account of the principal personages at the courts of Naples and France in her time, and of the careers of her sons and daughters (1910)
^In older literature and on her gravestone one finds the date 1763, but this is the birthyear of her elder sister Sara (May 23, 1763 – April 15, 1764) whose death was one of the reasons Moses Mendelssohn wrote the Phaedon. Cf. Alexander Altmann, Moses Mendelssohn, London 1973, Moses Mendelssohn, Jubilaeumsausgabe, Bd. 12,1, p. 43; letter to Thomas Abbt, May 1, 1764