Free logic resources for classroom or personal use

Readers may be interested in two free and freely available logic resources, both housed at my university, University of California Davis:

1. Paul Teller's A Modern Formal Logic Primer:The Primer was published in 1989 by Prentice Hall, since acquired by Pearson Education. Pearson Education has allowed the Primer to go out of print and returned the copyright to Teller, who now makes it available without charge for instructional and educational use.
   
2. Howard Pospesel and David Marans, Arguments: Deductive Logic Exercises: Similarly, the text has long been out of print, and the copyright has now reverted to the authors, who have generously made the book available to logic students, teachers, and the general public. Arguments is unique in that it can be used with any system of proofs for first-order predicate logic: truth trees, Fitch-style natural deductions, etc.

Please feel free to share information about similar free and freely available resources in the comments.