Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
hanh va » hang va, hanh vi
va nam » van nam, ha nam, va nay
va cau » van cau, va cac, va dau

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 y ((nang ma) or (nang x)) hoi. hieu va nam thuc va hanh va cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((nang ma) OR (nang x)) hoi. hieu va nam thuc va hanh va cau tren.
• Adding a wildcard symbol may retrieve word variants: tu sach y ((nang ma) or (nang x)) hoi. hieu va nam thuc va hanh va cau tren*.