Perhaps you should try some spelling variations:
su sach » so sach, vu sach
nang xa » lang xa, nang ma, mang xa
hieu vu » hieu va, hieu ve, hieu su
vu cham » va cham, vu kham, tu cham
han mai » han tai, ban mai, han mac
xuc va » duc va, tuc va, xac va
luc va » duc va, tuc va, loc 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: su sach y ((nang xa) or (nang x)) hoi. hieu vu cham ((xuc va) OR (luc va)) han mai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y ((nang xa) OR (nang x)) hoi. hieu vu cham ((xuc va) OR (luc va)) han mai va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y ((nang xa) or (nang x)) hoi. hieu vu cham ((xuc va) OR (luc va)) han mai va thiet".
• Adding a wildcard symbol may retrieve word variants: su sach y ((nang xa) or (nang x)) hoi. hieu vu cham ((xuc va) OR (luc va)) han mai va thiet*.