Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
dieu tra » dieu tri, kiem tra, dieu cua
tra tre » tran tren, tran tri, tran tro
nang xa » nang x, lang xa, nang ma
van anh » tuan anh, van minh
te sac » te sach, te cac, te san
sac ky » cac ky, sai ky
va can » va chan, va cac, va con
va cao » va cac, va co, va dao

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: te sac ky nang xa hoi. hieu ((va can) OR (va cao)) thuc ((van anh) OR (van thanh)) dieu tra tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sac ky nang xa hoi. hieu ((va can) OR (va cao)) thuc ((van anh) or (van thanh)) dieu tra tre~".
• Adding a wildcard symbol may retrieve word variants: te sac ky nang xa hoi. hieu ((va can) OR (va cao)) thuc ((van anh) or (van thanh)) dieu tra tre*.