Perhaps you should try some spelling variations:
cham duc » pham duc, cham soc, pham duy
nang xa » lang xa, nang ma, mang xa
hieu vu » hieu va, hieu ve, hieu su
vu cham » va cham, vu kham, tu cham
duc van » duc va, duc tan, duc manh
van han » van hanh, van phan, van nhan
vu sac » vu sach, vu san, va sac
sac ky » cac ky, sai ky
tai va » thai va, mai va, dai va
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sac ky ((nang xa) or (nang x)) hoi. hieu vu cham duc van han ((tai va) or (tri va)) thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sac ky ((nang xa) OR (nang x)) hoi. hieu vu cham duc van han ((tai va) OR (tri va)) thiet.
• Adding a wildcard symbol may retrieve word variants: vu sac ky ((nang xa) or (nang x)) hoi. hieu vu cham duc van han ((tai va) or (tri va)) thiet*.