Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
dang xay » dang van, van xay
tu sach » thu sach, su sach, te sach
hieu he » hieu ve, hiem he, hieu hien
danh vi » hanh vi, dinh vi, danh di
va danh » va dinh, va dan, va hanh
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
hieu le » hieu ve, hieu ly, tieu le
nang ma » tang ma, sang ma, nang cao
vi cua » vai cua, di 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 ky ((nang ma) or (dang xay)) hoi. ((hieu le) OR (hieu he)) nam thuc va danh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang ma) OR (dang xay)) hoi. ((hieu le) OR (hieu he)) nam thuc va danh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang ma) or (dang xay)) hoi. ((hieu le) OR (hieu he)) nam thuc va danh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang ma) or (dang xay)) hoi. ((hieu le) OR (hieu he)) nam thuc va danh vi cua tre*.