I almost harvested this one because I didn't already have a copy of the 0.50 stamp. Decided to google the guy who sent it,
Tr#7847;n V#259;n Khê (24 July 1921 - 24 June 2015) was a Vietnamese musicologist, academic, writer, teacher and performer of traditional music. He was father of the musician ethnomusicologist Tr#7847;n Quang H#7843;i [fr]. His La musique viêtnamienne traditionnelle (Paris, 1962) was for many years a standard text of Vietnamese musicology.
He was director of research at CNRS and professor at the Sorbonne, and in 2008 named a Honorary Member of the International Music Council of UNESCO where he is coordinator of the project "The Universe of Music, A History".