PARALLEL GOSPELS IN HARMONY - with STUDY GUIDE lets you read and study the four Gospels in parallel columns with corresponding passages side-by-side, using the modern language World English Bible. It's also copyright-free, so that anyone can reproduce it. A disciple in the garden of Gethsemane cuts off the ear of the high priest's servant according to all four Gospels. But only John tells us the servant's name, and that it was Peter who wielded the sword. And only Luke tells us that Jesus healed the wound. This book allows you to see all of this at a glance.
David A. Reed served for a decade as a contributing editor of Dr. Walter Martin's Christian Research Journal and has authored some twenty books on Bible topics. His most recent include Come, Follow Jesus!—the Real Jesus and DOORSTEP BIBLE Answering Mormons & Jehovah's Witnesses.
Like "The Gospel in Life," this book has each gospel in parallel columns. It is a bit different from TGIL in that the four-column format continues even when only one gospel covers an event (the other columns are left blank). This keeps the formatting neat and tidy and makes it clear to see which gospel covers which events. Reed does not offer much in the way of explanation for his methodology, but he doesn't make a lot of choices, instead, he presents disputed passages in both places - where something could be the same event or come later is presented twice. This lets you compare for yourself to see what you think.
The "study guide" is nothing more than questions with blanks, so that part isn't as helpful as I had hoped, but it does give you things to consider as you study.