Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
hanh dau » hang dau, danh dau, han dau
chat soc » chat hoc, chat doc, chat song
hieu van » hieu va, thien van, lieu va
nang xa » nang x, lang xa, nang ma
sach ty » sach y, sach tu, sach thu
sach ky » sac ky, sach y, sach kem
va hanh » van hanh, va thanh, va danh
dau su » dau tu, dan su, da su

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