As far as presenting sources are concerned, the book The life and exploits of Alexander the Great  sites much more sources in detail than source, which I think refers to some sources already referred by others. As such it is as credible as its own sources and not whether the Author is researcher of repute and printed by reputed publisher. Its credibility therefore lies in sources which are presented sparsely in the book perhaps, perhaps not. As far as the Author is concerned, in my understanding, he himself suggested that the story of Alexander that originated from Egypt should be considered more authentic than others ( reasons given as ..it is hardly likely that their writers and scribes would hasten to record his history, whereby they would also incidentally describe their own national defeat; to these countries, then, we must not look for the original Alexander story. Similarly, we must not look to the states of Greece for it, because at the death of Alexander the memory of their subjugation and the victorious deeds which he wrought for the glory of Macedon would be too fresh in the minds of their peoples. One country only could be the birthplace of the Alexander story, and that country was Egypt..). I am not sure if the general discussion is driven by this very idea i.e. keeping the Alexander story from Egypt as authentic (which the scholarship of the author has indeed explained so well along with origin of other sources, especially ones from Greece that perhaps dominate current understanding). This according to me, forms one of the essence of the Alexander story, and I hope someone clarifies which story is the Egypt story in the said book which I myself is unsure for I don't have that experience and skill to tell out the exact parts off Egypt origins. At the most I can only hope that someone will research into the Alexander story from Egypt, and not his fanboy fantasies from Greece, to put forth a credible understanding if not already done. Then perhaps someone can put up that as reliable secondary source on the internet and can be referred to here.