Perhaps you should try some spelling variations:
trinh khac » trinh khai, trinh kham, tinh khac
trinh nhan » trinh han, trinh phan, trinh nha
trinh khau » trinh khai, trinh kham, trinh han
trinh cao » trinh chao, trinh co, trinh cau
cuoi viet » nguoi viet, co viet, nuoc viet
nhan dang » nhan dan, phan dang, tran dang
cao luan » cao lan, cao quan, cao xuan
dang van » hoang van, hang va
hai viet » thai viet, mai viet, tai viet
oi viet » hoi viet, o viet, gioi viet
van bac » van ban, van bao, van hac
bac cay » bac can, bac cao, bac cau
cac cau » cac mau, bac cau, ca cau
luan va » luan van, luat va
ca cay » cua cay, cac cay, ca cac
cay co » cac co, tay co, cay cong
co hai » co dai, co hoi, o hai
cau co » cau do, cac co, dau co
va ca » va cao, va cai, va cau
co d » co do, co da, co pd

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