Perhaps you should try some spelling variations:
thuat sac » thuat sach, thuat san, thuat tac
hieu van » hieu va, thien van, lieu va
nang ma » sang ma, nang cao, mang may
tang ma » mang may, tang van
van cac » van hac, van cau, van bac
dat van » dao van, dat va, hat van
dam van » dao van, nam van, pham van
sac ky » cac ky, sai ky
vi cua » vai cua, di cua

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

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