Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
toc sach » hoc sach, doc sach, thuoc sach
nang van » dang van, tang van, lang van
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
van hoi » van hoa, van hoc, van hoe
hieu va » lieu va, hieu qua
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, dua tren

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