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.
Strongly recommended is the 19-page Guide to Picasso's Barcelona by Josep Maria Carandell (I got mine in the underground 'Ruta del Modernisme' shop in the Plaza de Catalunya - look for a big red 'i' sign. Also available from Picasso Museum and no doubt elsewhere). There's a virtual version based on this pamphlet on the MP site.
A review of early drawings has much on the Barcelona years. JSTOR citation:
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: