Perhaps you should try some spelling variations:
van cham » van chat, van tham, va cham
han thai » han tai, ban thai, van thai
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
thai va » thai van
nang xa » lang xa, nang ma, mang xa
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 van cham ((xuc va) OR (luc va)) han thai 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 van cham ((xuc va) OR (luc va)) han thai 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 van cham ((xuc va) OR (luc va)) han thai va thiet".
• Adding a wildcard symbol may retrieve word variants: su sach y ((nang xa) or (nang x)) hoi. hieu van cham ((xuc va) OR (luc va)) han thai va thiet*.