Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
hanh tri » thanh tri, hanh tai, hanh trinh
va hanh » van hanh, va thanh, va danh
bac loc » bac hoc
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
sac ky » cac ky, sai ky
loc va » hoc va, luc va
so sac » so sach, so dac

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

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