Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, tu cach
hanh di » hanh vi, hanh de, hang di
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
sang ma » tang ma, sang tao, mang may
nang ma » tang ma, nang cao, mang may
te sach » toc sach
di cua » dai cua, doi cua, de cua

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) OR (te sach)) loai ((nang ma) or (sang ma)) hoi. hieu van nam thuc va hanh di cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) loai ((nang ma) OR (sang ma)) hoi. hieu van nam thuc va hanh di cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (te sach)) loai ((nang ma) or (sang ma)) hoi. hieu van nam thuc va hanh di cua vat".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (te sach)) loai ((nang ma) or (sang ma)) hoi. hieu van nam thuc va hanh di cua vat*.