Perhaps you should try some spelling variations:
trinh cao » trinh chao, trinh co, trinh cau
hoi viet » hai viet, oi viet, thai viet
cao lanh » cao lan, cao anh, cao danh
toi viet » thi viet, tai viet, oi viet
doi viet » dai viet, oi viet, do viet
cao cac » cho cac, cao cap, ca cac
luan va » luan van, luat va
lanh va » hanh va, anh va, lanh dao
cac co » cac cong
va cao » va cac, va co, va dao
lan va » lan van, lang va, ban va
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) or (luan va)) cao cac co ((toi viet) OR (hoi 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) OR (luan va)) cao cac co ((toi viet) OR (hoi 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) or (luan va)) cao cac co ((toi viet) OR (hoi 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) or (luan va)) cao cac co ((toi viet) OR (hoi viet)) nam ) or ( chuong trinh cao lanh va cao cac co doi viet nam ))*.