Perhaps you should try some spelling variations:
nang khai » dang khai, nang hai, quang khai
thuat sac » thuat sach, thuat san, thuat tac
hieu van » hieu va, thien van, lieu va
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
nuoc van » nuoc va, nuoc san, luoc van
van nang » van quang, van ban, van dong
khai cua » thai cua, hai cua, khi cua
nang xa » lang xa, nang ma, mang xa
van cac » van hac, van cau, van bac
sac ky » cac ky, sai ky
cua tu » cua tuc, cua su, cua cu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sac ky ((nang xa) or (nang x)) hoi. hieu van cac nuoc van nang khai cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sac ky ((nang xa) OR (nang x)) hoi. hieu van cac nuoc van nang khai cua tu.
• Adding a wildcard symbol may retrieve word variants: thuat sac ky ((nang xa) or (nang x)) hoi. hieu van cac nuoc van nang khai cua tu*.