Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
duy sang » duy van, duy can, duy anh
hieu van » hieu va, thien van, lieu va
lai cua » dai cua, hai cua, lai chau
va danh » va dinh, va hanh, dia danh
van cam » van nam, van lam, van cau
cam duc » cam xuc, cao duc, pham duc
cua tre » cua te, cuu tre, cua triet
va dan » ca dan, va dao, va dau

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 ((duy sang) or (ty xang)) xa hoi. hieu van cam duc ((va danh) OR (va dan)) lai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((duy sang) OR (ty xang)) xa hoi. hieu van cam duc ((va danh) OR (va dan)) lai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((duy sang) or (ty xang)) xa hoi. hieu van cam duc ((va danh) OR (va dan)) lai cua tre*".