Humboldt an <persName xmlns="http://www.tei-c.org/ns/1.0" ref="https://edition-humboldt.de/H0013206 http://d-nb.info/gnd/11852240X">Johann Friedrich von Cotta</persName>, <placeName xmlns="http://www.tei-c.org/ns/1.0" ref="https://edition-humboldt.de/H0005221 https://www.geonames.org/2950159">Berlin</placeName>, 3. Mai 1806, <bibl xmlns="http://www.tei-c.org/ns/1.0" corresp="https://edition-humboldt.de/KGM28M3V">Humboldt 2009</bibl>, 73.