This is the link Wikipedia provides:I actually don't know what the frontiers would have been, so could I get a description of them?
Imperial Rivals
Based on archival research, this is a history of the Russo-Chinese border which examines Russia's expansion into the Asian heartland during the decades of Chinese decline and the 20th-century paradox of Russia's inability to sustain political and economic sway over its domains.
books.google.com
Haven't checked the rest of the link to see if there's a map tucked in there somewhere...