I suppose Italy should be one of the best (if not THE best) place to look  
for a history of accountancy and of the equilibrium concept in it. As you  
probably know, Luca Paciolo's 1494 Summa "institutionalized" the  
double-entry book-keeping system. 
 
You should try to contact the people at the Italian Society for the History of  
Accounting (I heard of them because they recently held an international  
workshop here in Pisa). Their website is www.sisronline.it and I think they  
have some internationally-oriented young researchers whom you could exchange  
ideas with. 
 
Nicola Giocoli