Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
thuc van » thuc vat, thuc dan, thuc va
cam thuc » am thuc, nam thuc, cam thu
sach ky » sac ky, sach y, sach ty
so sach » so sanh, bo sach, co sach
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
doi va » hoi va, noi va, dai va
va cam » va cham, va cac, va cao
di va » dai va, di vao, di vat

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 ky ((nang xa) OR (nang ma)) hoi. hieu va cam thuc van hanh ((di va) or (doi va)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky ((nang xa) OR (nang ma)) hoi. hieu va cam thuc van hanh ((di va) OR (doi va)) triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky ((nang xa) OR (nang ma)) hoi. hieu va cam thuc van hanh ((di va) or (doi va)) triet*".