Perhaps you should try some spelling variations:
thien van » thi van
van hanh » van thanh, ban hanh, van anh
tang van » dang van, hoang van, trong van
van dau » van dao, phan dau
hai cua » thai cua, dai cua, hoi cua
va hanh » va thanh, va danh, ban hanh
dau tuc » dau tu, dao tuc, cau truc
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
tang ma » mang may
cua tre » cua te, cuu tre, cua triet

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 ((tang ma) or (tang van)) hoi. thien van dau tuc ((va hanh) OR (van hanh)) hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((tang ma) OR (tang van)) hoi. thien van dau tuc ((va hanh) OR (van hanh)) hai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((tang ma) or (tang van)) hoi. thien van dau tuc ((va hanh) OR (van hanh)) hai cua tre*".