Perhaps you should try some spelling variations:
thanh duc » than duc, thinh duc, thanh dung
thach duc » thach thuc, than duc, thinh duc
hieu van » hieu va, thien van, lieu va
hanh dai » hanh tai, hanh dao, vanh dai
te sach » toc sach
sach ky » sac ky, sach y, sach ty
cao hoc » co hoc, cho hoc, chat hoc
va hanh » van hanh, va thanh, va danh
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: te sach ky nang ((cao hoc) or (cau hoi)). hieu van ((thanh duc) OR (thach duc)) va hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang ((cao hoc) OR (cau hoi)). hieu van ((thanh duc) OR (thach duc)) va hanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang ((cao hoc) or (cau hoi)). hieu van ((thanh duc) OR (thach duc)) va hanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky nang ((cao hoc) or (cau hoi)). hieu van ((thanh duc) OR (thach duc)) va hanh dai cua tre*.