Ok, you have been auditioning files and have saved some as candidates for future work. Of course, you probably documented them all and made notes about the content. If not, and you are faced with
and you want to know which were in E minor, then you could do this
which is handy,
To find out more go to http://www.alphabase.co.uk/state-file-mysteries/ to down load part 1 of this thrilling document.