Perhaps you should try some spelling variations:
ve triet » va trien, su triet
sach thu » sach thue, sach thieu, sach tham
thanh vi » hanh vi, thanh va, thanh ve
va thanh » gia thanh, ban thanh, va tinh
cao duc » dao duc, cao suc, giao duc
cau duc » cau luc, chu duc, cau truc
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
sang ma » tang ma, nang ma, sang tao
vi ve » va ve, gi ve, ve ve

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach thu ((mang may) or (sang ma)) hoi. hieu va ((cau duc) OR (cao duc)) va thanh vi ve triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach thu ((mang may) OR (sang ma)) hoi. hieu va ((cau duc) OR (cao duc)) va thanh vi ve triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach thu ((mang may) or (sang ma)) hoi. hieu va ((cau duc) OR (cao duc)) va thanh vi ve triet".
• Adding a wildcard symbol may retrieve word variants: su sach thu ((mang may) or (sang ma)) hoi. hieu va ((cau duc) OR (cao duc)) va thanh vi ve triet*.