(Basic Text 1) Lang, S.: "Algebra," third edition, Springer-Verlag,
U.S.A. (2002), ISBN 038795385X.
Remarkably, this book can now be downloaded for
free as a .djvu file: http://bookos.org/g/Serge%20Lang .
I would be careful about checking any files of
this kind for viruses, though.
You can also buy a hard copy for $67.82 from Amazon.
The book may be available at the Penn bookstore,
but keep in mind that the bookstore marks up all books
by 33 per cent.
(Basic Text 2) Dummit, D.S. and Foote, M.: "Abstract algebra,"
third edition, Wiley, U.S.A., (2004), ISBN 0-471-43334-9.
A google search will show various web sites which
claim to have free downloads of this book, but be
careful about viruses. Amazon advertises the book
for $70.83, which is far lower than the price of Wiley.
(Optional) Artin, M.: "Algebra," Prentice Hall, U.S.A., (1991)
This book is available free at http://bookos.org/g/algebra+textbooks .
One can find $15 hard cover versions, e.g. at
Comments: The Dummit and Foote text provides a more compact but
less complete presentation of the text than does Lang's book. Artin's book
has a better discussion of matrix groups and of some other topics, such
as groups defined by generators and relations. I will suggest readings from all
three texts, as well as from some journal articles, for different parts of the