Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
sach thu » sach thue, sach tham, cach thuc
nang mai » nang ma, nang tai, lang mai
vai cua » dai cua, hai cua, lai cua
cao duc » dao duc, cao suc, giao duc
mai hoi » mai khoi, dai hoi, lai hoi
qua cao » qua cac, qua ca, qua cai
va dan » ca dan, va dao, va dap
va dau » va dao

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 thu) OR (sach thieu)) nang mai hoi. hieu qua cao duc ((va dan) or (va dau)) vai cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach thu) OR (sach thieu)) nang mai hoi. hieu qua cao duc ((va dan) OR (va dau)) vai cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach thu) OR (sach thieu)) nang mai hoi. hieu qua cao duc ((va dan) or (va dau)) vai cua triet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach thu) OR (sach thieu)) nang mai hoi. hieu qua cao duc ((va dan) or (va dau)) vai cua triet*.