Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thien van » thi van
cua viet » ca viet, hoa viet, cua vat
cao hoi » cau hoi, cao hoc, tao hoi
hac duc » hoc duc, thach duc, pham duc
va hanh » van hanh, va thanh, va danh
y nang » ky nang, ly nang, v nang
co hoi » co hoc, co loi
ha duc » ho duc, ha dac, xa duc
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: thuoc sach y nang ((cao hoi) OR (co hoi)). thien van ((hac duc) or (ha duc)) va hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach y nang ((cao hoi) OR (co hoi)). thien van ((hac duc) OR (ha duc)) va hanh vi cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach y nang ((cao hoi) OR (co hoi)). thien van ((hac duc) or (ha duc)) va hanh vi cua viet".
• Adding a wildcard symbol may retrieve word variants: thuoc sach y nang ((cao hoi) OR (co hoi)). thien van ((hac duc) or (ha duc)) va hanh vi cua viet*.