Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
sach ky » sac ky, sach y, sach ty
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
hieu va » hieu qua
duc ban » duc tan, dua ban, duc man
duc van » duc va, duc tan, duc manh
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: hoc sach ky lang xa hoi. ((hieu va) OR (lieu va)) cham ((duc ban) or (duc van)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky lang xa hoi. ((hieu va) OR (lieu va)) cham ((duc ban) OR (duc van)) hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ky lang xa hoi. ((hieu va) OR (lieu va)) cham ((duc ban) or (duc van)) hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: hoc sach ky lang xa hoi. ((hieu va) OR (lieu va)) cham ((duc ban) or (duc van)) hanh vi cua tre*.