Perhaps you should try some spelling variations:
trinh cau » trinh chat, trinh chao, trinh tu
trinh cao » trinh chao, trinh co, tinh cao
doi viet » dai viet, hoi viet, oi viet
tai viet » thi viet, mai viet, tai lieu
hai viet » thai viet, mai viet, dai viet
cau luan » cu luan, dau luan, lau luan
cau giay » cuu giai, cac giai
soi viet » hoi viet, oi viet, noi viet
cao cay » cao cap, cho cay, tao cay
cao cao » cao cap, bao cao, tao cao
van cao » van dao, van bao, van hao
so viet » hoc viet
van van » van ban, tan van, san van
cao so » cao son, cao su, cao do
van va » van vat, ban va, van ha
cay co » cac co, tay co, cay cong

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 ((van va) OR (van van)) ((cau xay) or (cau giay)) co ((soi viet) or (doi viet)) nam ) or ((( chuong trinh cau luan van cao cao so ((hai viet) or (tai viet)) nam ) or ( chuong trinh cau luan van cao cay co so viet nam ))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( cong trinh cao ((van va) OR (van van)) ((cau xay) OR (cau giay)) co ((soi viet) OR (doi viet)) nam ) OR ((( chuong trinh cau luan van cao cao so ((hai viet) OR (tai viet)) nam ) OR ( chuong trinh cau luan van cao cay co so viet nam )))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( cong trinh cao ((van va) OR (van van)) ((cau xay) or (cau giay)) co ((soi viet) or (doi viet)) nam ) or ((( chuong trinh cau luan van cao cao so ((hai viet) or (tai viet)) nam ) or ( chuong trinh cau luan van cao cay co so viet nam ))))".
• Adding a wildcard symbol may retrieve word variants: (( cong trinh cao ((van va) OR (van van)) ((cau xay) or (cau giay)) co ((soi viet) or (doi viet)) nam ) or ((( chuong trinh cau luan van cao cao so ((hai viet) or (tai viet)) nam ) or ( chuong trinh cau luan van cao cay co so viet nam ))))*.