The research paper  "Is a Secondary Currency Essential?- On the Welfare Effects of a New Currency" by Max Fuchs and Jochen Michaelis has been published in the journal "Jahrbücher für Nationalökonomie und Statistik" (Journal of Economics and Statistics) . 

In their paper they examine the welfare effects of a second currency. The paper appeared in Volume 243 Issue 2 and is available here (open access).