Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
sach thi » sach thu, sach tai, sach thieu
thi nang » thi cong, ki nang, thi hanh
nang lai » nang tai, mang lai, nang cai
va danh » va dinh, va hanh, dia danh
tu sach » thu sach, su sach, te sach
lai roi » lai hoi, loi roi
va cao » va co, va dao, va bao
va dan » ca dan, va dao, va dau
vai va » mai va, dai va, hai va

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach thi nang lai roi. hieu ((va cao) OR (va cac)) duc ((va danh) or (va dan)) vai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thi nang lai roi. hieu ((va cao) OR (va cac)) duc ((va danh) OR (va dan)) vai va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach thi nang lai roi. hieu ((va cao) OR (va cac)) duc ((va danh) or (va dan)) vai va triet".
• Adding a wildcard symbol may retrieve word variants: tu sach thi nang lai roi. hieu ((va cao) OR (va cac)) duc ((va danh) or (va dan)) vai va triet*.