Helmersen, Peter
born 1838; died 1877Brief von Fedor P. Litke an Karl Ernst von Baer, 06.10.1872 [6te Octob. 1872]
Sankt Petersburg, 06/10/1872Brief von Fedor P. Litke an Karl Ernst von Baer, 21.02.1876 [21 Februar 1876]
Sankt Petersburg, 21/02/1876