Perhaps you should try some spelling variations:
doc sac » doc sach, dac sac, hoc sach
hieu va » lieu va, hieu qua
va danh » va dinh, va dan, dia danh
va hanh » van hanh, va thanh, ban hanh
luu tre » luu tru, cuu tre, luy tre
hieu ve » hieu van
cao hoi » cau hoi, co hoi, cao hoc
sac ky » cac ky, sai ky
vi luu » vi lua

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sac ky nang cao hoi. ((hieu ve) OR (hieu va)) cam xuc ((va hanh) or (va danh)) vi luu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sac ky nang cao hoi. ((hieu ve) OR (hieu va)) cam xuc ((va hanh) OR (va danh)) vi luu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sac ky nang cao hoi. ((hieu ve) OR (hieu va)) cam xuc ((va hanh) or (va danh)) vi luu tre".
• Adding a wildcard symbol may retrieve word variants: doc sac ky nang cao hoi. ((hieu ve) OR (hieu va)) cam xuc ((va hanh) or (va danh)) vi luu tre*.