Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
banh vai » hanh vi, hanh va, anh va
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
nam cuc » nam cac, nam cua, nam thuc
cuc ban » cua ban, cac ban, cuu ban
cua tre » cua te, cuu tre, cua triet

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 xa) or (nang ma)) hoi. hieu van nam cuc ban ((banh vai) or (ban va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky ((nang xa) OR (nang ma)) hoi. hieu van nam cuc ban ((banh vai) OR (ban va)) cua tre.
• Adding a wildcard symbol may retrieve word variants: thu sach ky ((nang xa) or (nang ma)) hoi. hieu van nam cuc ban ((banh vai) or (ban va)) cua tre*.