Help needed : Don Rosa's stories creation dates

[Nicolas Roudier]

I'm looking for the creation dates of all the Don Rosa's stories.
It's impossible to find (inducks, etc...). Only the publication date is (not 
always the month) mentionned.

I ask Keno about that and he told me that he never kept these information.

Does anybody  have it ? Or knows a mean to reach it ?
Maybe ask the publishing companies ? I think there are archives somewhere...