Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
hanh lai » hanh lam, hanh tai, thanh lap
pham duy » pham duc
van pham » san pham, van phan, van phat
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
nang ma » tang ma, nang cao, mang may
sach ty » sach y, sach tu, sach thu
sang ma » tang ma, sang tao, mang may
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, dua tren
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 ((sang ma) or (nang ma)) hoi. hieu van pham duy va hanh lai ((cua tre) or (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty ((sang ma) OR (nang ma)) hoi. hieu van pham duy va hanh lai ((cua tre) OR (cua triet)).
• Adding a wildcard symbol may retrieve word variants: toc sach ty ((sang ma) or (nang ma)) hoi. hieu van pham duy va hanh lai ((cua tre) or (cua triet))*.