Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
va doanh » van doanh, vay doanh, va danh
sang ma » tang ma, sang tao, mang may
nang ma » tang ma, nang cao, mang may
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cac xuc » cam xuc, cac nuoc, chat xuc
cuc tre » cua tre, cuu tre, cuc thue
duc tre » duoc tren, duc tien
ve cac » va cac, vien cac
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: hoc sach ky ((sang ma) or (nang ma)) hoi. hieu ve cac xuc va doanh tai ((cuc tre) OR (duc tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky ((sang ma) OR (nang ma)) hoi. hieu ve cac xuc va doanh tai ((cuc tre) OR (duc tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ky ((sang ma) or (nang ma)) hoi. hieu ve cac xuc va doanh tai ((cuc tre) OR (duc tre))".
• Adding a wildcard symbol may retrieve word variants: hoc sach ky ((sang ma) or (nang ma)) hoi. hieu ve cac xuc va doanh tai ((cuc tre) OR (duc tre))*.