Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
hieu van » hieu va, thien van, lieu va
hanh dau » hang dau, danh dau, han dau
chat hoc » chat hoa, chat thom, cho hoc
chat soc » cham soc, chat doc, chat song
sach ky » sach y, sach ty, sach kem
va hanh » van hanh, va thanh, va danh
dau cua » dai cua, day cua, cau cua
sac ky » cac ky, sai ky
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: vu ((sach ky) OR (sac ky)) nang x hoi. hieu van ((chat soc) or (chat hoc)) va hanh dau cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu ((sach ky) OR (sac ky)) nang x hoi. hieu van ((chat soc) OR (chat hoc)) va hanh dau cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu ((sach ky) OR (sac ky)) nang x hoi. hieu van ((chat soc) or (chat hoc)) va hanh dau cua viet".
• Adding a wildcard symbol may retrieve word variants: vu ((sach ky) OR (sac ky)) nang x hoi. hieu van ((chat soc) or (chat hoc)) va hanh dau cua viet*.