Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
thanh duc » thach duc, than duc, thinh duc
thanh doi » thanh loi, thanh moi, thanh do
hanh doi » hanh noi, hang doi, hanh moi
hieu van » hieu va, thien van, lieu va
su sach » vu sach
cao hoc » co hoc, cho hoc, chat hoc
vu nang » vuc nang, va nang, vu dang
so sach » so sanh, bo sach, co sach
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) OR (so sach)) vu nang cao hoc. hieu van thanh duc va ((hanh doi) or (thanh doi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) vu nang cao hoc. hieu van thanh duc va ((hanh doi) OR (thanh doi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (so sach)) vu nang cao hoc. hieu van thanh duc va ((hanh doi) or (thanh doi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) OR (so sach)) vu nang cao hoc. hieu van thanh duc va ((hanh doi) or (thanh doi)) cua tre*.