Perhaps you should try some spelling variations:
trinh cao » trinh chao, trinh co, trinh cau
toi viet » thi viet, hoi viet, oi viet
tai viet » thi viet, mai viet, tai lieu
cao lanh » cao anh, cao danh, cay lanh
doi viet » dai viet, hoi viet, oi viet
cao lan » cao van, cao dang, cao tang
cao cac » cho cac, cao cap, ca cac
lanh va » hanh va, anh va, lanh dao
lan va » luan va, lan van, lang va
va cao » va cac, va co, va dao
cac co » cac cong
co doi » cho doi, co dot, co dai

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( cong trinh cao lan va cao cac co ((toi viet) OR (tai viet)) nam ) or ( chuong trinh cao lanh va cao cac co doi viet nam ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( cong trinh cao lan va cao cac co ((toi viet) OR (tai viet)) nam ) OR ( chuong trinh cao lanh va cao cac co doi viet nam )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( cong trinh cao lan va cao cac co ((toi viet) OR (tai viet)) nam ) or ( chuong trinh cao lanh va cao cac co doi viet nam ))".
• Adding a wildcard symbol may retrieve word variants: (( cong trinh cao lan va cao cac co ((toi viet) OR (tai viet)) nam ) or ( chuong trinh cao lanh va cao cac co doi viet nam ))*.