Perhaps you should try some spelling variations:
thuc dang » thuoc dang, thuc dan, thuc dung
dang hanh » dang thanh, ban hanh, dang van
lang van » dang van, hoang van, giang van
tang van » dang van, hoang van, trong van
cam thuc » am thuc, nam thuc, cam thu
hieu ve » hieu va, hieu van
doi cua » dai cua, hoi cua
su cac » tu cac, su cao, su can
ve cam » ve cham, ve cac, va cam
vi cua » vai cua, di cua

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: su cac ky ((lang van) OR (tang van)) hoi. hieu ve cam thuc dang hanh ((vi cua) OR (doi cua)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su cac ky ((lang van) OR (tang van)) hoi. hieu ve cam thuc dang hanh ((vi cua) or (doi cua)) tre~".
• Adding a wildcard symbol may retrieve word variants: su cac ky ((lang van) OR (tang van)) hoi. hieu ve cam thuc dang hanh ((vi cua) or (doi cua)) tre*.