Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
so sach » so sanh, bo sach, co sach
vai cua » dai cua, hai cua, lai cua
va danh » va dinh, va hanh, dia danh
cau luc » cau truc, cau phuc
hieu va » lieu va, hieu qua
dang xa » dang xay, lang xa, dang ha
cua tre » cua te, cuu tre, cua triet
va cau » van cau, va cac, va dau
va dan » ca dan, va dao, va dau
y dang » ky dang, 2 dang, _ dang

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((so sach) or (hoc sach)) y dang xa hoi. hieu va cau luc ((va danh) OR (va dan)) vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (hoc sach)) y dang xa hoi. hieu va cau luc ((va danh) OR (va dan)) vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sach) or (hoc sach)) y dang xa hoi. hieu va cau luc ((va danh) OR (va dan)) vai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (hoc sach)) y dang xa hoi. hieu va cau luc ((va danh) OR (va dan)) vai cua tre*.