Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
nam thuc » nam thuoc, am thuc, nam thu
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
hieu va » lieu va, hieu qua
mai hoi » mai khoi, dai hoi, lai hoi
cam ky » cac ky
ma hoi » xa hoi, ma hoa, me hoi
va nam » van nam, ha nam, va nay
vi dau » vi dai, va dau, bi dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((cam ky) OR (cao ky)) nang ((ma hoi) or (mai hoi)). hieu va nam thuc va hanh vi dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((cam ky) OR (cao ky)) nang ((ma hoi) OR (mai hoi)). hieu va nam thuc va hanh vi dau tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((cam ky) OR (cao ky)) nang ((ma hoi) or (mai hoi)). hieu va nam thuc va hanh vi dau tren*".