Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
lang xa » lang ha, dang xay, lang van
van cau » van dau, van hau, van chat
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
do van » dao van, vo van, so van
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky ((nang ma) or (lang xa)) hoi. hieu van cau do van hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((nang ma) OR (lang xa)) hoi. hieu van cau do van hanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((nang ma) or (lang xa)) hoi. hieu van cau do van hanh di cua tre*.