Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
truc van » truc va, thuc van, truc ban
dang xay » dang van, van xay
cac truc » cau truc, cac tru, cac trung
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
dang xa » lang xa, dang ha, dang va
vai va » mai va, dai va, lai va
hai va » hai van, thai va, hoi va
ve cac » va cac, vien cac

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