Perhaps you should try some spelling variations:
va thanh » gia thanh, ban thanh, va tinh
hieu van » hieu va, thien van, lieu va
thanh va » thanh van, hanh va, thanh ha
cau tren » cu tren, dau tren, ca tren
te sach » toc sach
sach ky » sac ky, sach y, sach ty
van bao » van ban, van dao
bao duc » dao duc, bao luc, cao duc
cuu tre » cua tre, cau treo
x hoi » xa hoi, o hoi, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ky nang ((x hoi) OR (x ho)). hieu van bao duc va thanh va ((cuu tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang ((x hoi) OR (x ho)). hieu van bao duc va thanh va ((cuu tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang ((x hoi) OR (x ho)). hieu van bao duc va thanh va ((cuu tre) or (cau tren))".
• Adding a wildcard symbol may retrieve word variants: te sach ky nang ((x hoi) OR (x ho)). hieu van bao duc va thanh va ((cuu tre) or (cau tren))*.