Must an Expert Witness's Opinion be "Supported by Cited Literature"?

Aug 2004 – Article
Intellectual Property Today, Vol. 11, No. 8 at page 12,

Velander v. Garner, 348 F.3d 1359, 68 USPQ2d 1769 (Fed. Cir. 2003) (opinion by Circuit Judge Schall joined by Circuit Judge Prost; dissenting opinion by Circuit Judge Gajarsa2), apparently approves a panel of the BPAI’s3 having given no weight to the opinions of the expert witnesses of either of the parties because those opinions were not “supported by cited literature.” However, the panel of the BPAI then went on to grant the motion of the party whose expert witness it had denigrated (based on the expert opinions of the APJs), and the panel of the CAFC approved that, too.