Among the King James Version Apocrypha, there is a certain book, called Second Esdras, which is found neither in the Masoretic Text, nor in the Greek Septuagint; its first two and last two chapters are independent sections, called the Fifth and Sixth Books of Ezra, while the middle portion, spanning from the third to the fourteenth chapter, forms what is usually labeled as Fourth Ezra.
Whilst researching various scholarly books and articles, freely available online, relating to the textual criticism of 5 Ezra (2 Esdras 1-2), I was somewhat surprised to discover that the work is usually perceived as forming a monolithic unit, being commonly regarded as an early Christian work. While distinctly and unequivocally Christian elements are indeed found within the text's present form, thus partially explaining the aforementioned view, what struck me as rather odd was that not even a single scholar, from among the ones I had access to, appeared particularly inclined to question, or cast as much as the tiniest shadow of doubt, on this seemingly universally accepted thesis; which only brings me to my question:
Are there any peer-reviewed scholarly works, questioning the alleged internal unity of 5 Ezra (2 Esdras 1-2) ?
(After all, it could well be that either my Google skills are lacking, or that such works might not be freely available online).