Perhaps you should try some spelling variations:
su sach » so sach, vu sach
dinh vi » dinh ve, dinh viet, dinh tri
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
ky sang » ky nang, ky dang, ky tang
ta hai » tai hai, tac hai, tra hai
ve cam » ve cham, ve cac, va cam
va hai » van hai, va chai, va khai
luc va » tuc va, loc va
vi cua » vai cua, di cua
cua te » cua tu

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 ky sang ((va hai) or (ta hai)). hieu ve cam ((luc va) OR (duc va)) dinh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky sang ((va hai) OR (ta hai)). hieu ve cam ((luc va) OR (duc va)) dinh vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky sang ((va hai) or (ta hai)). hieu ve cam ((luc va) OR (duc va)) dinh vi cua te".
• Adding a wildcard symbol may retrieve word variants: su sach ky sang ((va hai) or (ta hai)). hieu ve cam ((luc va) OR (duc va)) dinh vi cua te*.