Perhaps you should try some spelling variations:
dau tren » dau tien, dat tren, dau tieng
van hanh » van thanh, ban hanh, van anh
cam thuc » am thuc, nam thuc, cam thu
va hanh » va thanh, va danh, ban hanh
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
cam ky » cao ky, cac ky
ve cam » ve cham, ve cac, va cam
ma hoi » xa hoi, ma hoa, me hoi
vi dau » vi dai, va dau, bi dau
tu cam » tu cham, tu cac, tu nam

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: tu cam ky nang ((ma hoi) OR (mai hoi)). hieu ve cam thuc ((va hanh) OR (van hanh)) vi dau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu cam ky nang ((ma hoi) or (mai hoi)). hieu ve cam thuc ((va hanh) OR (van hanh)) vi dau tren~".
• Adding a wildcard symbol may retrieve word variants: tu cam ky nang ((ma hoi) or (mai hoi)). hieu ve cam thuc ((va hanh) OR (van hanh)) vi dau tren*.