Four Highly Dispersed Millisecond Pulsars Discovered in the Arecibo PALFA Galactic Plane Survey - Crawford, F.; Stovall, K.; Lyne, A.; Stappers, B.; Nice, D.; Stairs, I.; Lazarus, P.; Hessels, J.; Freire, P.; Allen, B.; Bhat, Ramesh; Bogdanova, S.; et al. (Institute of Physics Publishing, Inc., 2012)