Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
sach ty » sach y, sach thu, xach tay
sach tu » sach thu, cach tu, sach uu
nang xa » nang x, lang xa, nang ma
dau tuc » dao tuc, cau truc, dau nuoc
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de 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: su ((sach ty) OR (sach tu)) nang xa hoi. lieu va ((dau tuc) OR (dau tu)) van hanh di cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) or (sach tu)) nang xa hoi. lieu va ((dau tuc) OR (dau tu)) van hanh di cua tre~".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sach tu)) nang xa hoi. lieu va ((dau tuc) OR (dau tu)) van hanh di cua tre*.