Perhaps you should try some spelling variations:
trinh khau » trinh khai, trinh kham, trinh khac
trinh cao » trinh chao, trinh co, trinh cau
tran dang » tran quang, tran hoang, tranh hang
nhan dang » nhan dan, phan dang
khau luan » khoa luan, phap luan, pham luan
co nguoi » cho nguoi, con nguoi, o nguoi
hai viet » thai viet, mai viet, tai viet
cao luan » cao lan, cao quan, cao xuan
sach mau » sach dau, sach dao, bach mai
dot viet » dat viet, do viet, doc viet
cac cau » cac mau, bac cau, ca cau
cac cay » cac cam, cac cap, tac cay
cua cau » chua cau, cua cac, cua chu
van cac » van hac, van cau, van bac
ca cay » cua cay, ca cac, ca cao
van ca » van cau, van cua, dan ca
co hai » co dai, co hoi, o hai
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 luan van ((((cac cau) or (cua cau))) or (sach mau)) co hai viet nam ) or ((( cong trinh khau luan van ca cay co dot viet nam ) or ( cong trinh ((nhan dang) or (tran dang)) van cac cay co nguoi viet nam ))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( cong trinh cao luan van ((((cac cau) OR (cua cau))) OR (sach mau)) co hai viet nam ) OR ((( cong trinh khau luan van ca cay co dot viet nam ) OR ( cong trinh ((nhan dang) OR (tran dang)) van cac cay co nguoi viet nam )))).
• Adding a wildcard symbol may retrieve word variants: (( cong trinh cao luan van ((((cac cau) or (cua cau))) or (sach mau)) co hai viet nam ) or ((( cong trinh khau luan van ca cay co dot viet nam ) or ( cong trinh ((nhan dang) or (tran dang)) van cac cay co nguoi viet nam ))))*.