@book{Breuning2012,
author = {Breuning, Markus},
year = {2012},
language = {ger},
language = {eng},
language = {spa},
copyright = {http://www.fu-berlin.de/sites/refubium/rechtliches/Nutzungsbedingungen},
title = {Bibliographie über Alexander von Humboldt},
url = "http://dx.doi.org/10.17169/refubium-20782",
}