Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
ban hanh » ban hang
qua cham » qua hai, qua cac, qua cua
cua tre » cua te, cua triet, dua tren
cuc ban » cua ban, cac ban, cuu ban
va cham » va chat, va tham
sach ky » sac ky, sach y, sach ty
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
cuu tre » cau tren, cau treo

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 ((qua cham) OR (va cham)) cuc ban hanh vi ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky lang xa hoi. hieu ((qua cham) OR (va cham)) cuc ban hanh vi ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ky lang xa hoi. hieu ((qua cham) OR (va cham)) cuc ban hanh vi ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: hoc sach ky lang xa hoi. hieu ((qua cham) OR (va cham)) cuc ban hanh vi ((cua tre) or (cuu tre))*.