Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
mai khoi » mai khoa, tai khoa, cac khoi
doc sach » hoc sach, toc sach, nuoc sach
hieu va » lieu va, hieu qua
cac dac » cac dan, cac dai, cac bac
va danh » va dinh, va dan, va hanh
danh vi » hanh vi, dinh vi, danh di
cac duc » cac du, cao duc, cac nuoc
y nang » ky nang, ly nang, v nang
vi cua » vai cua, di cua

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

• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach y nang ((xa hoi) OR (mai khoi)). hieu va ((cac duc) OR (cac dac)) va danh vi cua triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach y nang ((xa hoi) or (mai khoi)). hieu va ((cac duc) OR (cac dac)) va danh vi cua triet~".
• Adding a wildcard symbol may retrieve word variants: doc sach y nang ((xa hoi) or (mai khoi)). hieu va ((cac duc) OR (cac dac)) va danh vi cua triet*.