This link contains a bibliography
http://mockingbird.creighton.edu/NCW/olsen.htm
of Tillie Olsen's works, quotations from interviews, and critical commentary on Yonnondio.
This link
http://www.afsc.org/pwork/0799/0701.htm
is a reprint of a syllabus Olsen herself used when she taught "The Literature of Poverty, Oppression, Revolution and the Struggle for Freedom" at Amherst College in 1969. This list is fascinating for a number of reasons: it shows the books that Olsen herself read and respected, and it also reflects the reading material of students during the struggles of the late 1960s. The books listed would serve as great secondary sources for a research paper on Olsen's political involvement or narrative polemics.
This essay addresses an oft-neglected element of Olsen's work:
http://www4.gvsu.edu/books/archive/riddle/lyons.htm
the role of Judaism in her characters' lives and the author's own life.