source of cross-references for kjv pure cambridge edition

Zak

I was wondering if anyone could tell me what the source is of the in-text cross-references for the kjv pure cambridge edition? 

King James Version

• Publisher: Logos Research Systems
• Publication Date: 2009

This King James Version is based upon the Pure Cambridge Edition first published around 1900. It has been carefully typeset to remove any typographical errors and accurately reflects the original text.

I am using the Logos app for iPad. And what I'm referring to are the IN-TEXT cross-references that are found in the above King James Version. (as the other Bibles available have their own in-text cross-references, which are different from the other Bibles)

Thanks!

Bradley Grainger (Logos)

Although I don't know for sure that this is the case, they appear to be the same as the cross-references that are in The Cambridge Paragraph Bible of the Authorized English Version (AV 1873). That resource has a large foreword that covers the history of the references (as well as many other details): logosres:av1873;ref=Page.p_lv;off=1213