In addition to a former thread this Unesco Tango Convention could be of historical interest. It´s a msWord doc, and since you have clicked the link, the download begins.
I have also scanned the 150 page presentation, with pictures, historical documents, stories etc. in Picasa here:
{This person had placed this on picassa web with this in the folder name blueheronbeauty/TangoUNESCO but unfortunately the resource does not appear to be available now. However, there is a page on their blog about Presentation to UNESCO for Tango}
You can use the zoom feature to see larger version of each page. There's so much great information, and wonderful pictures! I'm hoping, as I continue to find more documents, to expand the scans and make them available.