Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
van pham » san pham, van phan, van phat
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
duc van » duc va, duc tan, duc manh
hanh di » hanh vi, hanh de, danh di
hang di » hang doi, hang vi, hang dien
x hoi » xa hoi, o hoi, x ho

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 x hoi. hieu van pham duc van ((hanh di) or (hang di)) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. hieu van pham duc van ((hanh di) OR (hang di)) su triet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. hieu van pham duc van ((hanh di) or (hang di)) su triet*.