Perhaps you should try some spelling variations:
trinh phan » trinh han, trinh quan, thanh phan
trinh khau » trinh khai, trinh kham, trinh khac
trinh cao » trinh chao, trinh co, trinh cau
cuoi viet » nguoi viet, co viet, nuoc viet
khau luan » khoa luan, phap luan, pham luan
phan dang » phan dau, phan cong, nhan dan
dai viet » mai viet, dao viet, tai viet
dang van » hoang van, hang va
cao luan » cao lan, cao quan, cao xuan
bac cay » bac can, bac cao, bac cau
van bac » van ban, van bao, van hac
oi viet » hoi viet, o viet, gioi viet
cac dau » cac dan, cac du, cac dai
luan va » luan van, luat va
co dai » co dan, do dai
cay co » cac co, tay co, cay cong
ca cay » cua cay, cac cay, ca cac
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 dau co dai viet nam ) or ((( cong trinh khau luan va ca cay co d((oi viet) or (cuoi viet)) nam ) or ( cong trinh phan 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 dau co dai viet nam ) OR ((( cong trinh khau luan va ca cay co d((oi viet) OR (cuoi viet)) nam ) OR ( cong trinh phan 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 dau co dai viet nam ) or ((( cong trinh khau luan va ca cay co d((oi viet) or (cuoi viet)) nam ) or ( cong trinh phan dang van bac cay co ((oi viet) or (cuoi viet)) nam ))))*.