Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cua tre » cua te, cuu tre, cua triet
hanh de » hanh ve, hanh kem
sach ty » sach y, sach tu, sach thu
nang xa » nang x, lang xa, nang ma
luu van » cuu van, luan van, luu hanh
de cua » le cua, te cua, dieu cua
va cau » van cau, va cac, va dau
sac ky » cac ky, sai ky
ve cau » ke cau, ve cac, le cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sac ky) or (sach ty)) nang xa hoi. hieu ((ve cau) OR (va cau)) luu van hanh de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sac ky) OR (sach ty)) nang xa hoi. hieu ((ve cau) OR (va cau)) luu van hanh de cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sac ky) or (sach ty)) nang xa hoi. hieu ((ve cau) OR (va cau)) luu van hanh de cua tre*".