The Serious Christian Volumes 1–20 is a collection of 62 classic books (thousands and thousands of pages) by the founders and noteworthies of the Plymouth Brethren and Dispensational movements. This includes people like William Kelly, John Nelson Darby, F.W. Grant, etc. Half of these are commentaries on various books of the bible; the other half are theology.
This collection also includes the noteless NET Bible for bible cross references within these and other Logos Bible Software books. The benefit of this version of the NET Bible is that when it comes to copying and pasting into word, powerpoint, etc. you don't have to remove all those footnote references.
The NET Bible (New English Translation) is a completely new translation of the Bible Software books, not a revision or an update of a previous English version. It is being completed by more than twenty biblical scholars who are working directly from the best currently available Hebrew, Aramaic, and Greek texts.
These rare volumes are no longer available in print, but when they were, the cost of the complete set was hundreds of dollars.