noun
VERB + AUTHENTICITY
▪ cast doubt on , dispute , doubt , question
▪
Some have cast doubt on the ~ of the official version of events.
▪ ascertain , check , test
▪ certify , confirm , establish , prove , validate , verify
PHRASES
▪ a certificate of ~
▪
Despite its certificate of ~, the painting was a fake.
▪ a debate over the ~ of sth
▪
There has been some debate over the ~ of his will.
▪ of doubtful ~ ( esp. BrE ), of dubious ~ ( esp. AmE ), of questionable ~ ( esp. AmE )
▪
a document of doubtful ~