Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cam truc » cau truc, nam truc, lam truoc
cua viet » ca viet, hoa viet, cua vat
su sach » so sach, vu sach
ky lang » ky dang, ky tang, tay lang
hieu ve » hieu va
truc va » thuc va, thuc vat, trung va
va hanh » van hanh, va thanh, va danh
vi cua » vai cua, di cua

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

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