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

You may be able to get more results by adjusting your search query.

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