Perhaps you should try some spelling variations:
phan dau » phan tu, hang dau
cam thuc » am thuc, nam thuc, cam thu
va hanh » van hanh, va thanh, va danh
sang ma » tang ma, sang tao, mang may
nang ma » tang ma, nang cao, mang may
van dau » van dao
hieu ve » hieu va, hieu van
thuc va » thuc vat, thuc dan, thuc day
tu dan » tuc dan, tu ban, cu dan
dan ky » van ky
ve cam » ve cham, ve cac, va cam

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

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