Perhaps you should try some spelling variations:
thien van » thi van
tu sach » thu sach, su sach, te sach
dai cuu » dai cua, dai huu
va hanh » van hanh, va thanh, ban hanh
va danh » va dinh, va dan, dia danh
van cau » van dau, van hau, van chat
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, mang may
cuu tre » cua tre, cau tren, cau treo

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky ((nang ma) or (nang cao)) hoi. thien van cau truc ((va danh) OR (va hanh)) dai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang ma) OR (nang cao)) hoi. thien van cau truc ((va danh) OR (va hanh)) dai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang ma) or (nang cao)) hoi. thien van cau truc ((va danh) OR (va hanh)) dai cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang ma) or (nang cao)) hoi. thien van cau truc ((va danh) OR (va hanh)) dai cuu tre*.