I just noticed this old topic of mine got bumped up. We bought the Peterson's Eastern birds because we can play it on a standard CD player. A good old-fashioned relic.
But we've been finding this is limited because there is only one song and maybe one call for each bird. This is not always helpful for IDing birds because they can have more than one. We were thrown off earlier this year when we heard an Eastern Meadowlark with a chipping type call.
We bought the NA guide by Stokes and it came with a CD of 150 bird songs and calls. We can only play it in the van though because it is an MP3. If they had a standard CD, I would get the Stokes for Eastern or all of North America's birds, because they have multiple calls and songs for the birds.
We used to rhyme Plover with Rover, when Peterson's rhymed it with lover. Oh my, it was funny how we pronounced Bobolinks, boe-boe-links. It's Bob-oh-links. I am so glad I didn't talk to any birders before hearing some of these names.