Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
su triet » su viet, su tien, ve triet
sach ky » sach y, sach ty, sach kem
cao hoi » cau hoi, co hoi, cao hoc
luc van » luoc van, luu van, luc va
duc van » duc va, duc tan, duc manh
sac ky » cac ky, sai ky
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: te ((sach ky) or (sac ky)) nang cao hoi. hieu van nam ((luc van) OR (duc van)) hanh vi su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ky) OR (sac ky)) nang cao hoi. hieu van nam ((luc van) OR (duc van)) hanh vi su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ky) or (sac ky)) nang cao hoi. hieu van nam ((luc van) OR (duc van)) hanh vi su triet".
• Adding a wildcard symbol may retrieve word variants: te ((sach ky) or (sac ky)) nang cao hoi. hieu van nam ((luc van) OR (duc van)) hanh vi su triet*.