Perhaps you should try some spelling variations:
va trien » va truyen, va thiet, va tuyen
chat duc » chat xuc, chat doc, chet duoc
va triet » va thiet, ve triet, cua triet
van hang » van khang, van hoang, van thang
duc van » duc va, duc tan, duc manh
so sach » so sanh, bo sach, co sach
sach ty » sach y, sach tu, sach thu
hieu va » hieu qua
ty nang » ky nang, ty xang, ty hang
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ty nang x hoi. ((lieu va) or (hieu va)) chat duc van hang va ((va triet) OR (va trien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty nang x hoi. ((lieu va) OR (hieu va)) chat duc van hang va ((va triet) OR (va trien)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty nang x hoi. ((lieu va) or (hieu va)) chat duc van hang va ((va triet) OR (va trien))".
• Adding a wildcard symbol may retrieve word variants: so sach ty nang x hoi. ((lieu va) or (hieu va)) chat duc van hang va ((va triet) OR (va trien))*.