Perhaps you should try some spelling variations:
phap thuc » phap thu, phap hoc
hanh te » hanh tu, hanh ve, hanh de
va hanh » van hanh, va thanh, va danh
phap tu » phan tu, pham tu
sach ty » sach y, sach thu, xach tay
hieu ve » hieu va, hieu van
sach tu » sach thu, cach tu, sach uu
lang o » lang _, tang o, lang son
te cua » tue cua, le cua, de cua
cua te » cua tu
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach ty) or (sach tu)) lang o hoi. hieu ve ((phap thuc) OR (phap tu)) va hanh te cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach tu)) lang o hoi. hieu ve ((phap thuc) OR (phap tu)) va hanh te cua te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) or (sach tu)) lang o hoi. hieu ve ((phap thuc) OR (phap tu)) va hanh te cua te*".