Perhaps you should try some spelling variations:
khanh van » thanh van, khanh vinh, hanh va
dau tren » dau tien, dat tren, dau tieng
cam thuc » am thuc, nam thuc, cam thu
hanh van » thanh van, hanh va, hanh san
thuc va » thuc vat, thuc dan, thuc day
hieu ve » hieu va, hieu van
sang ma » tang ma, sang tao, mang may
nang ma » tang ma, nang cao, mang may
ve cam » ve cham, ve cac, va cam
dan ky » van ky
tu dan » tuc dan, tu ban, cu dan

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) OR (khanh van)) 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) OR (khanh van)) 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) OR (khanh van)) 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) OR (khanh van)) dau tren*.