Lee ebe e dere n'okpuru ebe a ma zaa ajụjụ a na-eso ya n'otu asụsụ ahụ e dere n'ebe ahụ: Ebe e dere: E hiwere ụlọ ọrụ ahụ na 6 (18) August 1845 na Saint Petersburg, Russia. Tupu Mgbanwe Russia nke 1917, a maara ya dị ka Imperial Russian Geographical Society. Ajụjụ: gịnị bụ ụlọ ọrụ ahụ hiwere na 1845
Ụlọ ọrụ Imperial Russian Geographical Society