She was the first European to walk all length of Ho Chi Minh trail, lived in Saigon undercover during American occupation and wrote couple of books about the Vietnam Wars.
She was telling a lot of stories and I remember some people from US visiting her in 90s hoping to use her contacts in order to find some lost American POWs.
Unfortunately her books had been not translated into English.
https://pl.wikipedia.org/wiki/Monika_Warne%C5%84ska
https://www.amazon.com/PFADE-DURCH-DEN-DSCHUNGEL-Vietnam-Rep...
https://en.wikipedia.org/wiki/Ho_Chi_Minh_trail
https://en.wikipedia.org/wiki/Cambodian%E2%80%93Vietnamese_W...