Perhaps you should try some spelling variations:
ve triet » va trien
su triet » su viet, su tien
van hanh » van thanh, ban hanh, van anh
van pham » san pham, van phan, van phat
hieu van » hieu va, thien van, lieu va
nang ma » tang ma, sang ma, nang cao
sach ky » sac ky, sach y, sach ty
duc van » duc va, duc tan, duc manh
mang xa » lang xa, mang may, dang xay
tu sach » thu sach, su sach, te sach

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