I also have the history of the ARP set that is available for $40. You can also read the first few chapters from WM Glasgow's History of the RP. He will give the 'R' part of the ARP history. He even covers the merger between the 'A's and the 'R's.
Here it is online. It is a downloadable (and searchable) PDF.
Here is a nice edition from RHB. (The introduction in this one is well worth the purchase
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