Perhaps you should try some spelling variations:
trinh chao » trinh chat, trinh han, trinh co
trinh nhan » trinh han, trinh phan, trinh nha
nhan dang » nhan dan, phan dang, tran dang
chao luan » khao luan, phap luan, khau luan
cao luan » cao lan, cao xuan, dao luan
cao quan » co quan, bao quan, cao xuan
doi viet » dai viet, hoi viet, do viet
cay cong » cac cong, cao cong, cau cong
dang va » dang van, dang vat, hang va
luan va » luan van, luat va
oi viet » hoi viet, o viet, cuoi viet
cay co » cac co, tay co
co hoi » co loi
ca cau » cac cau, can cau, cua cau
va ca » va cao, va cai, va cau

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 luan) or (cao quan)) va ca cau ((co hoi) OR (co hoc)) viet nam ) or ((( cong trinh chao luan va ca ((cay co) or (cay cong)) doi viet nam ) or ( cong trinh nhan dang va cac ((cay co) or (cay cong)) oi viet nam ))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( cong trinh ((cao luan) OR (cao quan)) va ca cau ((co hoi) OR (co hoc)) viet nam ) OR ((( cong trinh chao luan va ca ((cay co) OR (cay cong)) doi viet nam ) OR ( cong trinh nhan dang va cac ((cay co) OR (cay cong)) oi viet nam )))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( cong trinh ((cao luan) or (cao quan)) va ca cau ((co hoi) OR (co hoc)) viet nam ) or ((( cong trinh chao luan va ca ((cay co) or (cay cong)) doi viet nam ) or ( cong trinh nhan dang va cac ((cay co) or (cay cong)) oi viet nam ))))".
• Adding a wildcard symbol may retrieve word variants: (( cong trinh ((cao luan) or (cao quan)) va ca cau ((co hoi) OR (co hoc)) viet nam ) or ((( cong trinh chao luan va ca ((cay co) or (cay cong)) doi viet nam ) or ( cong trinh nhan dang va cac ((cay co) or (cay cong)) oi viet nam ))))*.