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

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