Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
te sach » toc sach
cam duc » cam xuc, cao duc, pham duc
hai cua » thai cua, dai cua, hoi cua
lai cua » dai cua, lai chau, thai cua
duc van » duc va, duc tan, duc manh
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
hieu ve » hieu van
nang o » nang co, nang ho, nang ro
o hoi » co hoi, o hoc, o hai

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 o hoi. ((hieu ve) OR (hieu va)) cam duc van hanh ((lai cua) or (hai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky nang o hoi. ((hieu ve) OR (hieu va)) cam duc van hanh ((lai cua) OR (hai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky nang o hoi. ((hieu ve) OR (hieu va)) cam duc van hanh ((lai cua) or (hai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: te sach ky nang o hoi. ((hieu ve) OR (hieu va)) cam duc van hanh ((lai cua) or (hai cua)) tre*.