Letters of Alexander von Humboldt written between the years 1827 and 1858 to Varnhagen von Ense [microform] : together with extracts from Varnhagen's diaries, and letters of Varnhagen and others to Humboldt
Humboldt, Alexander von, 1769-1859; Varnhagen von Ense, Karl August, 1785-1858; Kapp, Friedrich, 1824-1884; Assing, Ludmilla, d. 1880