Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
qua cham » qua hai, qua cac, va cham
sang ma » tang ma, sang tao, mang may
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, nang cao, mang may
so sach » so sanh, bo sach, co sach
dai va » mai va
doi va » hoi va, noi va

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ty ((nang ma) OR (sang ma)) hoi. hieu qua cham thuc van hanh ((dai va) or (doi va)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty ((nang ma) OR (sang ma)) hoi. hieu qua cham thuc van hanh ((dai va) OR (doi va)) triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty ((nang ma) OR (sang ma)) hoi. hieu qua cham thuc van hanh ((dai va) or (doi va)) triet*".