Perhaps you should try some spelling variations:
nang dum » nang du, nang dua, nang luc
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
tu cach » tu cac
dum cua » duy cua, dam cua, dung cua
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va
va nang » van nang, da nang, cam nang
thuc va » thuc vat, thuc dan, thuc day
cua te » cua tu
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cach) or (su sach)) ky nang ma hoi. ((hieu ve) OR (hieu van)) nam thuc va nang dum cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (su sach)) ky nang ma hoi. ((hieu ve) OR (hieu van)) nam thuc va nang dum cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cach) or (su sach)) ky nang ma hoi. ((hieu ve) OR (hieu van)) nam thuc va nang dum cua te".
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (su sach)) ky nang ma hoi. ((hieu ve) OR (hieu van)) nam thuc va nang dum cua te*.