|Note_en={{Dating|back}} Advertising for the [[Parker 51]] in both ''regular'' and ''demi-size'' reporting the [[Aero-metric Ink System]]. Mention also the ''[[Lustraloy]]'' cap, the [[Parker 21]] and some new ''[[Duo-fold]]''. | |Note_en={{Dating|back}} Advertising for the [[Parker 51]] in both ''regular'' and ''demi-size'' reporting the [[Aero-metric Ink System]]. Mention also the ''[[Lustraloy]]'' cap, the [[Parker 21]] and some new ''[[Duo-fold]]''. |