The Museu Picasso has a large collection the works Picasso produced there. The Museum has an excellent website and key works can be seen virtually.
Here is a link to a brochure accompanying an exhibition of Picasso's early works. It gives a useful outline of the Barcelona / Paris years.
A review of early drawings has much on the Barcelona years. JSTOR citation:
Picasso. Barcelona
The Burlington Magazine , Vol. 140, No. 1139 (Feb., 1998), pp. 147-149
Published by: The Burlington Magazine Publications, Ltd.
Article Stable URL: http://www.jstor.org/stable/887723
Slightly to one side (at least as far as individual works of art are concerned) is this discussion on Picasso's possible political affiliations. Helpful for background:
Picasso's Politics in Barcelona
The Art Bulletin , Vol. 69, No. 1 (Mar., 1987), pp. 133-136
Published by: College Art Association
Article Stable URL: http://www.jstor.org/stable/3051088
I hope to come back to this subject before long.