Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
tu thiet » tu thien, tu triet, thua thiet
sach ky » sach y, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cao duc » dao duc, cao suc, giao duc
duc van » duc va, duc tan, duc manh
hanh de » hanh ve, hanh kem
sac ky » cac ky, sai ky
va cao » va cac, va co, va dao
de tu » do tu

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 ky) or (sac ky)) nang xa hoi. hieu va cao duc van hanh de tu thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) nang xa hoi. hieu va cao duc van hanh de tu thiet.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) nang xa hoi. hieu va cao duc van hanh de tu thiet*.