Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
thanh hai » thanh phan, thanh hoa, thanh san
chat duc » chat xuc, chat doc, chet duoc
va trien » va truyen, va thiet, va tuyen
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
nang xa » nang x, lang xa, nang ma
hieu ve » hieu van
hieu va » lieu va, hieu qua
duc ban » duc tan, duc van, dua ban
hai va » hai van, thai va, hoi va

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty nang xa hoi. ((hieu ve) or (hieu va)) chat duc ban thanh hai va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty nang xa hoi. ((hieu ve) OR (hieu va)) chat duc ban thanh hai va trien.
• Adding a wildcard symbol may retrieve word variants: su sach ty nang xa hoi. ((hieu ve) or (hieu va)) chat duc ban thanh hai va trien*.