On 19.4.2014 the last pilot veteran, the Bolivian general Alberto Paz Soldán died at the age of 102 years. During the war he piloted Curtiss Hawk II fighter. He also wrote a book (available in Spanish) about the Bolivian Air Force in the Chaco war.
Here is in Spanish his obituary in Spanish, published on 20.4.2014:
http://www.eldeber.com.bo/fallece-al...-/140420204435
To many the Chaco war may be unknown, it was a war between Bolivia and Paraguay during the years 1932 - 1935. It was also the first war in South American continent, in which airplanes were used. There were also air combats between Bolivian and Paraguayan planes. There were a variety of different planes: Curtiss Hawk II, Fiat CR 20, Breguet XIX, Ju 52...
There is fairly little available about this in English. The wikipedia is considered often dubious source, but I think that the wikipedia article on this subject is fairly good:
http://en.wikipedia.org/wiki/Aerial_..._the_Chaco_War
Another source about this subject in English is:
http://bura.brunel.ac.uk/bitstream/2...+version+1.pdf
And a recommended book is:
Dagehorn, Dan: Latin American Air Wars 1912-1969.
In Spanish there are available these links:
http://www.taringa.net/posts/info/98...e-el-aire.html
http://amshistoria.blogspot.fi/2013/...uerra-del.html