Perhaps you should try some spelling variations:
hanh dai » hanh tai, hanh dao, vanh dai
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
van cau » van dau, van hau, van chat
truc va » thuc va, thuc vat, trung va
va hanh » van hanh, va thanh, va danh
va cau » va cac, va dau, va cao
dai su » dai sua, dai so, dan su

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

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