Laurence Houlgate, Ph.D., is an Emeritus Professor of Philosophy at California Polytechnic State University, San Luis Obispo where he was a beloved colleague and teacher. He wrote the guides after his retirement in order to keep a promise to his former students.
I have read parts of all of his study guides and the voice of a good teacher and scholar can be heard on every page. I highly recommend them. Just click on the picture to be taken to any of the low-cost guides. (Also, Professor Houlgate has a great philosophy blog.)
Finally, let me say that the modern philosophers above are some of my favorite thinkers in the Western tradition. Well worth becoming acquainted with them if you are not already.