Not quite so straightforward! The Base stamp is from the Russian Civil War, issued 1919 by the South Russia government of General Denikin. The surcharge is for General Wrangel refugee post issued in November 1920. I can't tell you the Scott number, but it's SG60 in the Russian Refugees Post section of Russia, Civil War Issues.
Value is minimal, if you're interested. They have all been reprinted for collectors and I don't know of any reliable way of telling the original and reprint apart.
Historical background can be found at
https://en.wikipedia.org/wiki/Pyotr_Wrangel