Perhaps you should try some spelling variations:
thai viet » thi viet, tai viet, mai viet
thoi viet » thoai viet, thi viet, thon viet
cac thoi » cac toi, cac hop, cac tro
cau giay » cuu giai, cac giai
soi viet » so viet, hoi viet, oi viet
trinh co » trinh do, trinh cong, trinh hoa
giao lan » gian lan, giao dan, xiao lan
tay cac » tai cac, tay bac, tap cac
coc soi » cot soi, cong soi
co thai » do thai, ca thai, co hai
cac tay » cac tac, cac tai, cac tap
giao la » giao li, giao ly, gia la
cac cay » ca cay, cac cam, cac cap
cay coc » cay co, cay cong
van cac » van hac, van cau, van bac
dan van » dang van, doan van, dao van
lan va » luan va, lanh va, lan van
co dan » co ban, ca dan, cao dang
ky lan » ky dan, ky la

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 ((giao lan) OR (giao la)) va cac tay cac thoi viet nam ) or ( cong trinh co dan van cac cay coc soi viet nam ))) or ( cong trinh ky lan va ((cau xay) or (cau giay)) co thai viet nam ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((( cong trinh ((giao lan) OR (giao la)) va cac tay cac thoi viet nam ) OR ( cong trinh co dan van cac cay coc soi viet nam ))) OR ( cong trinh ky lan va ((cau xay) OR (cau giay)) co thai viet nam )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(((( cong trinh ((giao lan) OR (giao la)) va cac tay cac thoi viet nam ) or ( cong trinh co dan van cac cay coc soi viet nam ))) or ( cong trinh ky lan va ((cau xay) or (cau giay)) co thai viet nam ))".
• Adding a wildcard symbol may retrieve word variants: (((( cong trinh ((giao lan) OR (giao la)) va cac tay cac thoi viet nam ) or ( cong trinh co dan van cac cay coc soi viet nam ))) or ( cong trinh ky lan va ((cau xay) or (cau giay)) co thai viet nam ))*.