edited on 07-Jun-12 01:17 AM 
I'm 99% sure that it is. The...
I'm 99% sure that it is. There's a couple of photos of an almost identical chair on p. 36 and 37 of the 1999 International Design Yearbook (let me know if you'd like a scan), by B&B and credited to Citterio. The one in the book has a slightly different underframe configuration, and also looks like it might be a slightly different size- I don't know whether they made a few different sizes or whether the one in the book is a prototype.. But in all other respects it's identical (feet, general proportions etc.), and so if yours has a B&B label, you can be pretty sure it's by Citterio.