To explore anti-mass frameworks, there are several useful texts available online. One is

The Anti-Mass: Methods of Organizing for Collectives
by the Red Sunshine Gang, Berkeley, CA 1970
Full text available
here
or also
here

Collective Organisation by John Englart
considers anti-mass organizing as well.

For titles with summaries, I'd suggest looking at the AK catalog which has both Anarchist and Situationist sections. This could be useful as the anti-mass pamphlets mentioned above seem to be cited a lot in anarchist and situationist literature web sites.

Guy Debord's Theory of the Derive elaborates on a social practice of drifting through varied ambiances either alone or in very small groups.

Library at Nothingness.org has a variety of anarchist and situationist texts online, including excerpts from Situationist International

If you want to take a more thorough look at Foucault's work, try
this, as it has a number of full text excerpts

Theory.org Foucault Page has an extremely thorough exploration of Foucault's life, work, and its influence, and is a generally great site for exploring critical theorists, their ideas, work, and influences.

A book mentioned here is Foucault: the Legacy, ed. Clare O'Farrell

I hope this helps!