Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
sang ma » tang ma, sang tao, mang may
lieu ha » lieu nha, lieu va, liem ha
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
nang ma » tang ma, nang cao, mang may
tai cao » thai cao, tai sao, tai cac
tao cao » bao cao, toan cao
tu sach » thu sach, su sach, te sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky ((nang ma) or (sang ma)) hoa. lieu ha nam thuc va hanh ((tai cao) OR (tao cao)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang ma) OR (sang ma)) hoa. lieu ha nam thuc va hanh ((tai cao) OR (tao cao)) tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang ma) or (sang ma)) hoa. lieu ha nam thuc va hanh ((tai cao) OR (tao cao)) tren*".