Perhaps you should try some spelling variations:
sach van » sach han, sach va, bach van
van nang » van quang, van ban, van dong
truc van » truc va, thuc van, truc ban
van hanh » van thanh, ban hanh, van anh
so sach » so sanh, bo sach, co sach
hieu ve » hieu va, hieu van
hanh de » hanh ve, hanh kem
cua tre » cuu tre, cua triet, dua tren
ve cau » ke cau, va cau, ve cac
cua te » cua tu
x hoi » xa hoi, o hoi, 5 hoi

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: so sach van nang ((x hoi) OR (x ho)). hieu ve cau truc van hanh de ((cua tre) OR (cua te))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach van nang ((x hoi) OR (x ho)). hieu ve cau truc van hanh de ((cua tre) or (cua te))~".
• Adding a wildcard symbol may retrieve word variants: so sach van nang ((x hoi) OR (x ho)). hieu ve cau truc van hanh de ((cua tre) or (cua te))*.