Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
thanh va » thanh van, thanh ha, thanh ve
thuc day » thuc dan, thuc vat
cam thuc » am thuc, nam thuc, cam thu
su sach » vu sach
hanh va » hang va, hanh vi
van cam » van nam, van lam, van cau
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
so sach » so sanh, bo sach, co sach
cuu tre » cua tre, cau tren, cau treo

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) OR (so sach)) ky tang ma hoa. hieu van cam thuc day ((thanh va) OR (hanh va)) cuu tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (so sach)) ky tang ma hoa. hieu van cam thuc day ((thanh va) OR (hanh va)) cuu tre~".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (so sach)) ky tang ma hoa. hieu van cam thuc day ((thanh va) OR (hanh va)) cuu tre*.