Perhaps you should try some spelling variations:
su sach » so sach, vu sach
nang xa » lang xa, nang ma, mang xa
hieu ve » hieu va, hieu van
ve chat » va chat, van chat
han tai » hang tai, nhan tai, van tai
xuc va » tuc va, luc va, xac va
tai va » thai va, mai va, tri 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 ve chat ((xuc va) OR (duc va)) han tai 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 ve chat ((xuc va) OR (duc va)) han tai 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 ve chat ((xuc va) OR (duc va)) han tai va thiet".
• Adding a wildcard symbol may retrieve word variants: su sach y ((nang xa) or (nang x)) hoi. hieu ve chat ((xuc va) OR (duc va)) han tai va thiet*.