Perhaps you should try some spelling variations:
trinh khau » trinh khai, trinh kham, trinh khac
trinh nhan » trinh han, trinh phan, trinh nha
khau luan » khoa luan, phap luan, pham luan
nhan dang » nhan dan, phan dang, tran dang
trinh cao » trinh chao, trinh co, trinh cau
dot viet » dat viet, do viet, doc viet
dang van » hoang van, hang va
hai viet » thai viet, mai viet, tai viet
cao luan » cao lan, cao quan, cao xuan
cua cau » chua cau, cua cac, cua chu
cac cay » cac cam, cac cap, tac cay
van cac » van hac, van cau, van bac
cac cau » bac cau, ca cau, cac cam
o nguoi » _ nguoi, cho nguoi, con nguoi
cac mau » cam mau, sach mau
cay co » cac co, tay co, cay cong
van ca » van cau, van cua, dan ca
ca cay » cua cay, ca cac, ca cao
o hai » co hai, so hai, o lai
cay o » cay mo, cay ot, cay so

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 (cac mau)) o hai viet nam ) or ((( cong trinh khau luan van ca cay co dot viet nam ) or ( cong trinh nhan dang van cac cay o 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 (cac mau)) o hai viet nam ) OR ((( cong trinh khau luan van ca cay co dot viet nam ) OR ( cong trinh nhan dang van cac cay o nguoi viet nam )))).
• Adding a wildcard symbol may retrieve word variants: (( cong trinh cao luan van ((((cac cau) or (cua cau))) or (cac mau)) o hai viet nam ) or ((( cong trinh khau luan van ca cay co dot viet nam ) or ( cong trinh nhan dang van cac cay o nguoi viet nam ))))*.