I'd like to know what other Bible scholars he references
Standard practice when one is referring to a consensus position is to refer to a few main sources (this is true in the sciences as well). If there is a consensus, then necessarily virtually everybody relevant agrees and there is no point in any exhaustive survey, particularly when (as in this case) the author is arguing against the consensus. That said, here are the main "in text" citations:
"...the
Gospel of the Ebionites is either an indiscriminate harmony of the Synoptics or a corruption of the Gospel of Matthew. Thus, W. L. Petersen says that the
Gospel of the Ebionites appears to have been harmonized, woven from traditions found in the Synoptic Gospels (Matthew, Mark, and Luke). H. Koester believes that a harmony of the Gospels of Matthew and Luke is not only in evidence in Justin and 2 Clement, but also in the
Gospel of the Ebionites. J. K. Elliott sees the
Gospel of the Ebionites as a generic harmony of the synoptic type. In a study devoted to the provenance of the
Gospel of the Ebionites, D. A. Bertrand sees the latter as a harmony of the three Synoptics (though with slight preference for Matthew), which was a precursor to Tatians
Diatessaron. The harmony theory has recently been echoed by D. Lührmann: Im Text [des Evangeliums der Ebionäer] finden sich Einzelzüge aus allen drei synoptischen Evangelien; . . . Wahrscheinlich handelt es sich um eine Evangelienharmonie. With regard to the influence of the Gospel of Matthew on the
Gospel of the Ebionites, Throckmortons Gospel Parallels is the most pronounced, referencing each passage in the
Gospel of the Ebionites to the First Gospel."
or if his work is more a theory
His work is speculative (theory is a rather laden term that I hesitate to use in this context), but that' why I used his paper: he disagrees with the consensus position but even his dissenting view doesn't give any evidence or indication that any Ebionite gospel was a basis for Matthew.
Further, as we know that the synoptics relied on at least one common source (the consensus view, despite challenges over the last 100+ years since Holtzmann, is that Matthew & Luke both used Mark as well as a second source Q), this would introduce yet
another source we'd have to explain in relation to the synoptics when there is no evidence (and much against the view) that the authors of any of the synoptics used whatever the "gospel of the Hebrews" was.
Origen and a few others claimed the Gospel of the Hebrews was the original Matthew and also that it excluded a birth narrative.
Here's Origen:
"If any one should lend credence to the Gospel according to the Hebrews, where the Saviour Himself says, My mother, the Holy Spirit took me just now by one of my hairs and carried me off to the great mount Tabor, he will have to face the difficulty of explaining how the Holy Spirit can be the mother of Christ when it was itself brought into existence through the Word. But neither the passage nor this difficulty is hard to explain. For if he who does the will of the Father in heaven Matthew 12:50 is Christ's brother and sister and mother, and if the name of brother of Christ may be applied, not only to the race of men, but to beings of diviner rank than they, then there is nothing absurd in the Holy Spirit's being His mother, every one being His mother who does the will of the Father in heaven." (
source)
