Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
ban hanh » ban hang
hac duc » hoc duc, ha duc, thach duc
so sach » so sanh, bo sach, co sach
tu lang » cu lang, tu lanh, xu lang
tu xang » ty xang, tu quang, tct xang
hieu va » lieu va, hieu qua
va hac » van hac, va khac, va cac
vi su » va su, ve su, ki su

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ((tu xang) OR (tu lang)) xa hoi. hieu va hac duc ((ban hanh) or (van ban)) vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((tu xang) OR (tu lang)) xa hoi. hieu va hac duc ((ban hanh) OR (van ban)) vi su triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((tu xang) OR (tu lang)) xa hoi. hieu va hac duc ((ban hanh) or (van ban)) vi su triet*".