Perhaps you should try some spelling variations:
su sach » so sach, vu sach
doan vi » doan va, don vi, doan thi
cam luc » cam xuc, cau luc
sach ky » sac ky, sach y, sach ty
hieu va » lieu va
sang ma » tang ma, nang ma, sang tao
ky sang » ky nang, ky dang, ky tang
ma hai » ta hai, va hai, xa hai
luc va » duc va, tuc va, loc va
dan vi » don vi, dan va, gan vi
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 ma hai. ((hieu va) or (hieu qua)) cam luc va ((dan vi) OR (doan vi)) cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky sang ma hai. ((hieu va) OR (hieu qua)) cam luc va ((dan vi) OR (doan vi)) cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky sang ma hai. ((hieu va) or (hieu qua)) cam luc va ((dan vi) OR (doan vi)) cua te".
• Adding a wildcard symbol may retrieve word variants: su sach ky sang ma hai. ((hieu va) or (hieu qua)) cam luc va ((dan vi) OR (doan vi)) cua te*.