Perhaps you should try some spelling variations:
han dong » hanh dong, phan dong, han duong
truc ban » thuc ban, truc dan, truoc bang
truc van » truc va, thuc van, truc dan
sach han » sach tham, sach danh, sach nang
so sach » so sanh, bo sach, co sach
hanh ve » hanh vi, hanh va, hanh kem
hieu ve » hieu va, hieu van
cuu tre » cua tre, cau tren, cau treo
ve cau » ke cau, va cau, ve cac
ve cuu » ve chu, ve cua, ve cum
o hoc » co hoc, mo hoc, so hoc
o hoi » co hoi, o hai, o hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach han dong ((o hoi) or (o hoc)). hieu ve cau ((truc van) or (truc ban)) hanh ve cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach han dong ((o hoi) OR (o hoc)). hieu ve cau ((truc van) OR (truc ban)) hanh ve cuu tre.
• Adding a wildcard symbol may retrieve word variants: so sach han dong ((o hoi) or (o hoc)). hieu ve cau ((truc van) or (truc ban)) hanh ve cuu tre*.