Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
te sach » toc sach
sach ky » sac ky, sach y, sach ty
tai cua » thai cua, tai cuc, tri cua
va hanh » van hanh, va thanh, va danh
xa hanh » xa thanh, xa khanh, da hanh
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
tang ma » mang may, tang van
sang ma » nang ma, sang tao, mang may
va nam » van nam, ha nam, va nay

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky ((sang ma) or (tang ma)) hoi. hieu va nam thuc ((xa hanh) OR (va hanh)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky ((sang ma) OR (tang ma)) hoi. hieu va nam thuc ((xa hanh) OR (va hanh)) tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((sang ma) or (tang ma)) hoi. hieu va nam thuc ((xa hanh) OR (va hanh)) tai cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((sang ma) or (tang ma)) hoi. hieu va nam thuc ((xa hanh) OR (va hanh)) tai cua tre*.