Perhaps you should try some spelling variations:
tan thanh » tran thanh, tang thanh, toan thanh
cau tren » cu tren, dau tren, ca tren
hieu van » hieu va, thien van, lieu va
thanh ve » hanh ve, thanh va, thanh vien
cua tre » cua te, cuu tre, cua triet
cao duc » dao duc, cao suc, giao duc
sach tu » sach thu, cach tu, sach ty
vu sach » vu bach, su sach, vu khach
nang xa » lang xa, nang ma, mang xa
van cao » van dao, van bao, van hao

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach tu ((nang xa) or (nang x)) hoi. hieu van cao duc tan thanh ve ((cua tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach tu ((nang xa) OR (nang x)) hoi. hieu van cao duc tan thanh ve ((cua tre) OR (cau tren)).
• Adding a wildcard symbol may retrieve word variants: vu sach tu ((nang xa) or (nang x)) hoi. hieu van cao duc tan thanh ve ((cua tre) or (cau tren))*.