Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cham luc » cham soc, nhan luc, cham cuu
cua tre » cua te, cuu tre, cua triet
hanh de » hanh ve, hanh kem
luc van » luoc van, luu van, duc van
vu cham » va cham, vu kham, tu cham
hieu vu » hieu va, hieu ve, hieu su
dai hoi » dai hoc, dai hai, dai moi
mai hoi » mai khoi, lai hoi, mai doi
sach ty » sach y, sach tu, sach thu
sac ky » cac ky, sai ky
de cua » le cua, te cua, dieu cua

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 ((mai hoi) OR (dai hoi)). hieu vu cham luc 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 ((mai hoi) OR (dai hoi)). hieu vu cham luc 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 ((mai hoi) OR (dai hoi)). hieu vu cham luc van hanh de cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((sac ky) or (sach ty)) nang ((mai hoi) OR (dai hoi)). hieu vu cham luc van hanh de cua tre*.