Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
nang cau » nang cao, hang cau, nang dau
nam thuc » nam thuoc, am thuc, nam thu
va thanh » gia thanh, ban thanh, va tinh
sach ky » sac ky, sach ty, sach kem
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
cua tre » cuu tre, cua triet, dua tren
va nam » van nam, ha nam, va nay
cua te » cua tu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach y)) nang cau hoi. hieu va nam thuc va thanh dai ((cua tre) OR (cua te))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sach y)) nang cau hoi. hieu va nam thuc va thanh dai ((cua tre) OR (cua te))~".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sach y)) nang cau hoi. hieu va nam thuc va thanh dai ((cua tre) OR (cua te))*.