Two recently discovered post cards written by Martel to his publisher provide new information on the date he completed the manuscript of the first volume of La France ignorée and on the progress of its printing.
Shaw, Trevor R..
Martel's La France ignorée: new information from two post cards to his publisher.
International Journal of Speleology,
Available at: https://digitalcommons.usf.edu/ijs/vol9/iss2/10