Perhaps you should try some spelling variations:
vat hanh » vat thanh, van hanh, va hanh
hai thuc » thai thuc, dai thuc, ha thuc
hieu van » hieu va, thien van, lieu va
cua tre » cua te, cuu tre, cua triet
van hai » van ha, van chat, van hanh
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
su xac » pu xac, su cac
vi cua » vai cua, di cua
su sac » su sach, su cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sac) OR (su xac)) ky ((nang xa) or (nang ma)) hoi. hieu van hai thuc vat hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sac) OR (su xac)) ky ((nang xa) OR (nang ma)) hoi. hieu van hai thuc vat hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sac) OR (su xac)) ky ((nang xa) or (nang ma)) hoi. hieu van hai thuc vat hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sac) OR (su xac)) ky ((nang xa) or (nang ma)) hoi. hieu van hai thuc vat hanh vi cua tre*.