Perhaps you should try some spelling variations:
dau truc » cau truc, doan truc, dau tu
dai truc » dai thuc, doan truc, dai trung
van hanh » van thanh, ban hanh, van anh
sach thu » sach thue, sach thieu, sach tham
hanh di » hanh vi, hanh de, hang di
sach ty » sach y, sach tu, xach tay
nang xa » nang x, lang xa, nang ma
cuu tre » cua tre, cau tren, cau treo
di cuu » di cau, di cua, dinh cuu

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) or (sach thu)) nang xa hoi. lieu va ((dau truc) OR (dai truc)) van hanh di cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach thu)) nang xa hoi. lieu va ((dau truc) OR (dai truc)) van hanh di cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) or (sach thu)) nang xa hoi. lieu va ((dau truc) OR (dai truc)) van hanh di cuu tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sach thu)) nang xa hoi. lieu va ((dau truc) OR (dai truc)) van hanh di cuu tre*.