title: Comment on "Intense superradiant x rays from a compact source using a nanocathode array and emittance exchange".
authors.affiliation: SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
authors.forename: G
authors.initials: G
authors.lastname: Stupakov
authors.forename: A
authors.initials: A
authors.lastname: Zholents
authors.forename: M S
authors.initials: MS
authors.lastname: Zolotorev