How often are books quoted outside of their own book? I am trying to put an estimation together of how much of the bible we have today. I know that there are multiple books missing from the bible.

1 Chr 29:29 Now the acts of David the king, first and last, behold, they are written in the book of Samuel the seer, and in the book of Nathan the prophet, and in the book of Gad the seer, (KJV)
Num. 21:14 Wherefore it is said in the book of the wars of the Lord, What he did in the Red sea, and in the brooks of Arnon, (KJV)

Further examples are in Jos 10:13, 1 Kng 11:41, 2 Chr 9:29 12:15 20:34 33:19, 1 Cor 5:9, and Jude 1:14.
My question is which books of the Bible are quoted by other books outside of their own pages, and how many times each?
If you are interested in an exhaustive listing of every verse quoted from the Old Testament in the New Testament (OT books quoted outside of their pages - in the NT), then I recommend looking here:

Parallel Passages in New Testament Quoted from Old Testament


The list contains not only the direct or indirect citations, but also the allusions which are particularly worthy of attention: and the passages are given in the order of the Books of the New Testament. (The list has been divided up into five parts to decrease the download time.)

There is also the: Analytical Table and Harmony of the Mosaic Law, Prophecies in the Pentateuch and Historical Books (vvs. prophecy was given &amp; vvs. it was fulfilled), and Probable Occasion When Each Psalm Was Composed that are of notable interest.

If you are asking about scriptures quoted that don't appear anywhere else in the Bible, see the listing below.



Lost books

The so-called lost books of the Bible are those documents that are mentioned in the Bible in such a way that it is evident they were considered authentic and valuable but that are not found in the Bible today. Sometimes called missing scripture, they consist of at least the following: 


book of the Wars of the Lord (Num. 21:14) 
book of Jasher (Josh. 10:13; 2 Sam. 1:18) 
book of the acts of Solomon (1 Kgs. 11:41) 
book of Samuel the seer (1 Chr. 29:29) 
book of Gad the seer (1 Chr. 29:29) 
book of Nathan the prophet (1 Chr. 29:29; 2 Chr. 9:29) 
prophecy of Ahijah (2 Chr. 9:29) 
visions of Iddo the seer (2 Chr. 9:29; 12:15; 13:22) 
book of Shemaiah (2 Chr. 12:15) 
book of Jehu (2 Chr. 20:34) 
sayings of the seers (2 Chr. 33:19) 
an epistle of Paul to the Corinthians, earlier than our present 1 Corinthians (1 Cor. 5:9) 
possibly an earlier epistle to the Ephesians (Eph. 3:3) 
an epistle to the Church at Laodicea (Col. 4:16) 
and some prophecies of Enoch, known to Jude (Jude 1:14) 


To these rather clear references to inspired writings other than our current Bible may be added another list that has allusions to writings that may or may not be contained within our present text but may perhaps be known by a different title; for example, 


the book of the covenant (Ex. 24:7) which may or may not be included in the current book of Exodus. 
the manner of the kingdom, written by Samuel (1 Sam. 10:25) 
the rest of the acts of Uzziah written by Isaiah (2 Chr. 26:22)




More at www.lds.org/scriptures/bd/lost-booksBlue Letter Bible Study Resources: Charts and Outlines