Hi,
I just added some information about this coin
https://en.numista.com/catalogue/pieces18635.html
I think the name should be changed from Denga to Deneshka which is in cyrillic on reverse.
I could not modify mintage years to 1850-1867 according to data from coin catalogue http://www.katalogmonet.pl/Katalog/Zabory-1795-1918/Zab%C3%B3r-rosyjski-1832-1864/Monety-rosyjcko-warszawskie-ze-znakiem-BM-1850-1864/Obiegowe-dp1?startpage=1
Could you please add mintage years 1850,1851, 1852, 1853 and 1854 for mint B.M. ?
Thanks,
Zet