Good books or sources for learning on logic?

[guitarlifter]

I want to become a better observer and analyst of the information that I take in and be able to form more proficient arguments, thoughts and statements. I regrettably never took a logic class other than math in college, and I'd like to read up on the subject. Could anyone point me in the right direction. Free sources are preferable, but books are welcome as well.

[heavenlyboy34]

Here's a mises academy course on it http://academy.mises.org/courses/logic/ I believe there are pdf books on mises.org as well about logic.

[libertygrl]

I'd check out this too. Pretty deep stuff: http://www.triviumeducation.com/

[IDefendThePlatform]

I thought this series was very helpful:
http://www.criticalthinking.org/pages/critical-thinking-teaching-students-how-to-study-and-learn-part-one/513