Perhaps you should try some spelling variations:
doanh cua » doanh luan
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, nang cao, mang may
sang ma » tang ma, sang tao, mang may
hieu va » lieu va, hieu qua
cac xuc » cam xuc, cac nuoc, chat xuc
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, tuc va, luc va

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky ((nang ma) or (sang ma)) hoi. hieu va cac xuc va ((doanh cua) or (doanh nhan)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang ma) OR (sang ma)) hoi. hieu va cac xuc va ((doanh cua) OR (doanh nhan)) cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang ma) or (sang ma)) hoi. hieu va cac xuc va ((doanh cua) or (doanh nhan)) cua tre*.