Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
van hanh » van thanh, ban hanh, van anh
nang ma » tang ma, nang cao, mang may
sang ma » tang ma, sang tao, mang may
hieu ve » hieu va, hieu van
va hanh » va thanh, va danh, ban hanh
so sach » so sanh, bo sach, co sach
sach v » sach va, sach y, sach 2
ve cau » ke cau, va cau, ve cac
vi va » vi van, vai va, vu va

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 v ((nang ma) OR (sang ma)) hoi. hieu ve cau truc ((va hanh) or (van hanh)) vi va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach v ((nang ma) OR (sang ma)) hoi. hieu ve cau truc ((va hanh) OR (van hanh)) vi va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach v ((nang ma) OR (sang ma)) hoi. hieu ve cau truc ((va hanh) or (van hanh)) vi va triet".
• Adding a wildcard symbol may retrieve word variants: so sach v ((nang ma) OR (sang ma)) hoi. hieu ve cau truc ((va hanh) or (van hanh)) vi va triet*.