Perhaps you should try some spelling variations:
phap thuc » phap thu, phap hoc
day hanh » day nhanh, day thanh, dao hanh
sach ky » sac ky, sach ty, sach kem
hanh di » hanh vi, hanh de, hang di
phap tu » phan tu, pham tu
hieu ve » hieu va, hieu van
cao hoi » cau hoi, co hoi, cao hoc
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de cua

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

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