Perhaps you should try some spelling variations:
truc tuan » truc quan, truc tuyen, trung tuan
sach van » sach han, sach va, bach van
so sach » so sanh, bo sach, co sach
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
ve cau » ke cau, va cau, ve cac
anh le » manh le, oanh le, anh ve
le cua » ly cua
o hoi » co hoi, o hai, o hoa
o hoc » co hoc, mo hoc, so hoc

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 van dong ((o hoi) or (o hoc)). hieu ve cau truc tuan anh le cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach van dong ((o hoi) OR (o hoc)). hieu ve cau truc tuan anh le cua tre.
• Adding a wildcard symbol may retrieve word variants: so sach van dong ((o hoi) or (o hoc)). hieu ve cau truc tuan anh le cua tre*.