Perhaps you should try some spelling variations:
cau thuc » cau truc, cuu thuc, can thuc
van nang » van quang, van ban, van dong
ban hanh » ban hang
thuc ban » thuoc ban, thuc dan, thu ban
hieu van » hieu va, thien van, lieu va
sach van » sach han, sach va, bach van
su sach » so sach, vu sach
cua tre » cua te, cua triet, dua tren
hanh de » hanh ve, hanh kem
hieu ve » hieu va
cuu tre » cau tren, cau treo
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach van nang x hoi. ((hieu ve) or (hieu van)) cau thuc ban hanh de ((cua tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach van nang x hoi. ((hieu ve) OR (hieu van)) cau thuc ban hanh de ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach van nang x hoi. ((hieu ve) or (hieu van)) cau thuc ban hanh de ((cua tre) OR (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: su sach van nang x hoi. ((hieu ve) or (hieu van)) cau thuc ban hanh de ((cua tre) OR (cuu tre))*.