Changes
Fixed function call.
if ( DOI ~= nil ) then DOI = " " .. doi(frame, DOI, DoiBroken) else DOI = "" end
if ( ID ~= nil ) then ID = " " .. ID else ID = "" end
if ( ISBN ~= nil ) then ISBN = " " .. internalinkidinternallinkid(frame, {label="ISBN",link="International Standard Book Number",prefix="Special:BookSources/",id=ISBN}) else ISBN = "" end
if ( ISSN ~= nil ) then ISSN = " " .. externalinkid(frame, {label="ISSN",link="International Standard Serial Number",prefix="//www.worldcat.org/issn/",id=ISSN}) else ISSN = "" end
if ( JFM ~= nil ) then JFM = " " .. externallinkid(frame, {label="JFM",link="Jahrbuch über die Fortschritte der Mathematik",prefix="http://www.zentralblatt-math.org/zmath/en/search/?format=complete&q=an:",id=JFM}) else JFM = "" end