Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
hanh lai » hanh lam, hanh tai, thanh lap
pham duy » pham duc
van pham » san pham, van phan, van phat
nang ma » tang ma, sang ma, nang cao
sach ty » sach y, sach tu, sach thu
rang ma » tang ma, sang ma, rang va
va hanh » van hanh, va thanh, va danh
lai cua » dai cua, hai cua, lai chau
cua tre » cua te, cuu tre, cua triet
duy va » duy vat, duy van, day va

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 ty ((rang ma) or (nang ma)) hoi. hieu van pham duy va hanh lai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty ((rang ma) OR (nang ma)) hoi. hieu van pham duy va hanh lai cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach ty ((rang ma) or (nang ma)) hoi. hieu van pham duy va hanh lai cua tre*.