Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
van hanh » van thanh, ban hanh, van anh
va danh » va dinh, va dan, va hanh
ly cong » ky cong, le cong, lo cong
li cong » bi cong, li song, lieu cong
hieu va » lieu va, hieu qua
vi cua » vai cua, di cua
va cam » va cham, va cac, va cao
cua te » cua tu

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

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