Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
tinh vi » trinh vi, tinh voi, tinh va
va tinh » may tinh
cac dai » cac dan, cac bai, can dai
cac dat » cac dan, cai dat, cac dac
sach ky » sach y, sach ty, sach kem
nang ma » tang ma, sang ma, nang cao
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: thu ((sach ky) or (sac ky)) nang ma hoa. hieu van ((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) OR (sac ky)) nang ma hoa. hieu van ((cac dat) OR (cac dai)) va tinh vi cua vat.
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) or (sac ky)) nang ma hoa. hieu van ((cac dat) or (cac dai)) va tinh vi cua vat*.