Reddit mentions of The Logic Manual

The thing about learning formal logic is that not all logic languages were created equal! Essentially each has its benefits and learning a system of logic requires a good amount of time to be able to use it effectively for proofs etc. If you decide to try another then a large portion of this effort is wasted. At uni we used this http://www.amazon.co.uk/Logic-Manual-Volker-Halbach/dp/0199587833 I didn't particularly enjoy logic but it's written for someone who's never started formal logic and I thought that his system for proving validity was pretty elegant (though it required some getting used to). If you're interested in pursing Volker then pm me and I'll try to dig up some materials for you.