Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
phan duc » pham duc, phan tu, phan dau
dang xay » dang van, van xay
tu sach » thu sach, su sach, te sach
duc van » duc va, duc tan, duc manh
va phan » van phan, va phat, va phap
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
mang xa » lang xa, mang may, mang cua
sach ky » sac ky, sach y, sach ty
su tien » su kien, su hien, tu tieng
vi su » va su, ve su, ki su

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 ((((mang xa) OR (dang xay))) or (nang ma)) hoi. hieu va phan duc van hanh vi su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((((mang xa) OR (dang xay))) OR (nang ma)) hoi. hieu va phan duc van hanh vi su tien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((((mang xa) OR (dang xay))) or (nang ma)) hoi. hieu va phan duc van hanh vi su tien".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((((mang xa) OR (dang xay))) or (nang ma)) hoi. hieu va phan duc van hanh vi su tien*.