Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
ky tang » ky nang, ky dang, kho tang
tang ma » mang may, tang van
hieu ve » hieu va, hieu van
cam tuc » cam xuc, cam tu, dam thuc
so sac » so sach, so dac
vi hoc » li hoc, va hoc
dan vi » doan vi, don vi, dan va
va dan » ca dan, va dao, va dau
sac ky » cac ky, sai ky
ma hoi » mai hoi, xa hoi, ma hoa

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

• If you are trying to use Boolean operators, they must be ALL CAPS: so sac ky tang ma hoi. hieu ve ((cam tuc) OR (nam thuc)) va dan vi hoc (hien OR bien)~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sac ky tang ma hoi. hieu ve ((cam tuc) or (nam thuc)) va dan vi hoc (hien OR bien)~".
• Adding a wildcard symbol may retrieve word variants: so sac ky tang ma hoi. hieu ve ((cam tuc) or (nam thuc)) va dan vi hoc (hien OR bien)*.