Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, hieu ve
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
cac dat » cac dan, cai dat, cac dac
cac dai » cac dan, cac bai, can dai
va tinh » may tinh
tinh vi » trinh vi, tinh voi, tinh va
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: thu sach ky nang ma hoa. ((hieu van) or (lieu va)) ((cac dat) OR (cac dai)) va tinh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ma hoa. ((hieu van) OR (lieu va)) ((cac dat) OR (cac dai)) va tinh vi cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang ma hoa. ((hieu van) or (lieu va)) ((cac dat) OR (cac dai)) va tinh vi cua vat".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ma hoa. ((hieu van) or (lieu va)) ((cac dat) OR (cac dai)) va tinh vi cua vat*.