Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hang tai » hang va, dung tai
va hang » van hang, va nang, va lang
nang ma » tang ma, sang ma, mang may
cua tre » cuu tre, cua triet, dua tren
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
cac lop » cac hop, cac loai
ve cac » va cac, vien cac
lop va » lap va, hop va, nop va
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: thu sach ky ((nang ma) or (nang cao)) hoi. hieu ve cac lop va hang tai ((cua tre) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((nang ma) OR (nang cao)) hoi. hieu ve cac lop va hang tai ((cua tre) OR (cua te)).
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((nang ma) or (nang cao)) hoi. hieu ve cac lop va hang tai ((cua tre) or (cua te))*.