Buy the books over there. In HCMC they sell all the Viet books you want, new, used, photocopied, cheap. Checked the photocopied to see if all the pages are legible. I had a VN phrase book and tried, but our pronunciation is difficult for a VN person to understand. Many of the children want to try their English on you anyway. Unless you really get off the beaten track, someone will speak a little English. Have fun!