Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hanh dai » hanh tai, hanh dao, vanh dai
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
qua bac » qua ban, qua cac, cua bac
bac hoc » bai hoc, bac ho
hoc van » hoc dan, hoc va, hoc vat
sac ky » cac ky
cua tu » cua tuc, cua su, cua cu

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 (sai ky)) ((nang xa) or (lang xa)) hoi. hieu qua bac hoc van hanh dai cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sac ky) OR (sai ky)) ((nang xa) OR (lang xa)) hoi. hieu qua bac hoc van hanh dai cua tu.
• Adding a wildcard symbol may retrieve word variants: te ((sac ky) or (sai ky)) ((nang xa) or (lang xa)) hoi. hieu qua bac hoc van hanh dai cua tu*.