Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
van hanh » van thanh, ban hanh, van anh
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, mang may
hieu va » lieu va, hieu qua
cac dat » cac dan, cac dai, cac dac
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 sach ky ((nang ma) OR (nang cao)) hoi. hieu va ((cac dat) or (cai dat)) van hanh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sach ky ((nang ma) OR (nang cao)) hoi. hieu va ((cac dat) OR (cai dat)) van hanh vi cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sach ky ((nang ma) OR (nang cao)) hoi. hieu va ((cac dat) or (cai dat)) van hanh vi cua vat".
• Adding a wildcard symbol may retrieve word variants: thuat sach ky ((nang ma) OR (nang cao)) hoi. hieu va ((cac dat) or (cai dat)) van hanh vi cua vat*.