Perhaps you should try some spelling variations:
su sach » so sach, vu sach
ty mang » ty xang, tin mang, tri mang
ty hang » ly hang, ty xang, thi hang
hieu va » lieu va, hieu qua
cac duc » cac du, cac dac, cac nuoc
cao duc » dao duc, cao suc, giao duc
va hanh » van hanh, va thanh, va danh
vi va » vi van, vai va, vu va
thiet* » thieu*

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 ((ty mang) OR (ty hang)) xa hoi. hieu va ((cac duc) or (cao duc)) va hanh vi va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ty mang) OR (ty hang)) xa hoi. hieu va ((cac duc) OR (cao duc)) va hanh vi va thiet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ty mang) OR (ty hang)) xa hoi. hieu va ((cac duc) or (cao duc)) va hanh vi va thiet*".