Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
tho nang » thi nang, ho nang, cho nang
thu bang » thu ban, thu hang, chu bang
va hanh » van hanh, va thanh, ban hanh
va danh » va dinh, va dan, dia danh
te sach » toc sach
va giao » van giao, va giai, va gia
mai hoi » mai khoi, dai hoi, lai hoi
hieu va » lieu va, hieu qua
vai su » va su, van su, lai su

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ((tho nang) or (thu bang)) mai hoi. hieu va giao duc ((va danh) OR (va hanh)) vai su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((tho nang) OR (thu bang)) mai hoi. hieu va giao duc ((va danh) OR (va hanh)) vai su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((tho nang) or (thu bang)) mai hoi. hieu va giao duc ((va danh) OR (va hanh)) vai su triet".
• Adding a wildcard symbol may retrieve word variants: te sach ((tho nang) or (thu bang)) mai hoi. hieu va giao duc ((va danh) OR (va hanh)) vai su triet*.