This brief IMF perspective is a good start (using the Euro as example):

https://www.imf.org/external/pubs/ft/fandd/2014/03/orourke.htm

The mian point is in the following quote which specifies the critical requirements for success of a single currency:

The currency area is too large and diverse—and given the need for periodic real exchange rate adjustments, the anti-inflation mandate of the European Central Bank (ECB) is too restrictive. Labor mobility between member countries is too limited to make migration from bust to boom regions a viable adjustment option. And there are virtually no fiscal mechanisms to transfer resources across regions in the event of shocks that hit parts of the currency area harder than others.

Dear James, Thanks for sharing constructive insight on constraint in implementation of single currency in EU. It sounds challenging for fostering effective management of single currency as development disparity among member countries might partly affect the ultimate goal.

I think that polish economy will be not ready to adopt single currency for nedxt few, or even 10 years. Since 1st May 2004 our economy strengthened, but it is still to weak to compete with West-European countries economies. In accordance with the Accession Treaty Republic of Poland became also a member of the Economic and Monetary Union, but my country received special status, which shall be derogate in undetermined time. Only the United Kingdom and Danemark are free to decide on the single currency, they still have GBP and DKK because of the possibility of 'opt out' clause - according to the principle of differentiated integration.

https://www.google.pl/publicdata/explore?ds=ml9s8a132hlg_&met_y=minimum_wage&fdim_y=currency:eur&hl=pl&dl=pl&idim=country:sk:hr:ro#!ctype=l&strail=false&bcs=d&nselm=h&met_y=minimum_wage&fdim_y=currency:eur&scale_y=lin&ind_y=false&rdim=country&idim=country:sk:hr:pl:uk:fr:es:ie&ifdim=country&hl=pl&dl=pl&ind=false

Thanks Aleksandra for Poland specific case.The differentiated integration may help member country to prepare for joining single currency cooperation. It may take time to fully integrate with the old members.

https://www.academia.edu/1841746/David_Fields_and_Matias_Vernengo_2012_Hegemonic_currencies_during_the_crisis_The_dollar_versus_the_euro_in_a_Cartalist_perspective_Review_of_International_Political_Economy_

Dear David, Thanks for your contributing paper.It sounds interesting. I will look into it.

Hi Choen, my pleasure!

For the European Union it was a major *political* project as well (de Grauwe 2013).* I think the Nobel Prize lecture by Thomas Sargent on "United States then and Europe now" holds valuable insights. He discusses the challenges of monetary and fiscal union:

http://www.nobelprize.org/mediaplayer/index.php?id=1741

*) http://www.annualreviews.org/doi/abs/10.1146/annurev-polisci-060911-085923