D. Rivera, Siqueiros + A - appreciate, please

[Пелагея Ларина]

Dear forum users!
Two works by Diego Rivera and one Alfaro Siqueiros planned to sell.
I would like to understand the possible price range, here in Russia.
I would also appreciate any advice and recommendations on this issue.

These papers were presented by the authors in 1955godu, in Moscow, the mother of a close friend of our family. G. Fomin (photo 1) - Spanish Jew, of the number of "ever" Spanish children were brought to the USSR in 1937. during the Spanish Civil War. She was raised in foster care. Friends, and corresponded with Siqueiros and Rivera, was their personal interpreter in Moscow.
 
1-2. Diego Rivera. "B /n", 1935. 38.5 h27, mixed media (watercolor)
Signature: «My dear friend Gale St. Thomas. November 7th 1955. »
3-4. Diego Rivera. "W /o" 1955., 28h34, w /ink.
Signature: «Gale St. Thomas with appreciation» (hereinafter, the right-signature difficult to read)
5. Alfaro Siqueiros. "View of the volcano Popocatepetl," 1955, 29h44, c /c /Tempera (?).
(The work was written in Moscow in 1955.)

Photos from the family archives.
1.Diego Rivera and his wife (left) and Fomin (right). Moscow 1955.
2. Diego Rivera in a Moscow clinic ("the Kremlin »-?), 1955.