Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
cam tuc » cam xuc, cam tu, dam thuc
sach ky » sac ky, sach ty, sach kem
nang co » nang cao, nang doc, nang noi
cu tren » tu tren, dua tren
co loi » co hoi
va dan » ca dan, va dao, va dau
ca cu » ca cua, cua cu, ca cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach ky) or (sach y)) nang co loi. hieu van ((cam tuc) OR (nam thuc)) va dan ca cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sach y)) nang co loi. hieu van ((cam tuc) OR (nam thuc)) va dan ca cu tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sach y)) nang co loi. hieu van ((cam tuc) OR (nam thuc)) va dan ca cu tren".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sach y)) nang co loi. hieu van ((cam tuc) OR (nam thuc)) va dan ca cu tren*.