Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
ban hanh » ban hang
thuc ban » thuoc ban, thuc dan, thu ban
cau thuc » cau truc, cuu thuc, can thuc
nang doc » nang luc
sach thu » sach thue, sach thieu, sach tham
van cau » van dau, van hau, van chat
nang co » nang cao, nang noi, nang hoc
hang co » hang cho, hang ca, lang co
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di 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 thu ((hang co) or (((nang co) or (nang doc)))) loi. hieu van cau thuc ban hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach thu ((hang co) OR (((nang co) OR (nang doc)))) loi. hieu van cau thuc ban hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach thu ((hang co) or (((nang co) or (nang doc)))) loi. hieu van cau thuc ban hanh vi cua tre*.