When Oman first wrote about the battle he understood that the French advanced in column. At a later date he came to a different conclusion. I know others on the Forum will have the particulars of when and how he changed his opinion. You can start with this article here: http://www.napoleon-series.org/military/organization/maida/c_maida2.html. The whole article is worth reading but the information about Oman's change of opinion is about one third of the way down this particular page.
Plug "Maida" into the search function on the website http://www.napoleon-series.org/search/c_search.html, and you will get all sorts of references in the Forum archives as well as articles.
As for books, I have a copy of "Maida: A Forgotten Victory" by John Stewart, Pentland Press, 1997. It is rather thin at 82 pages total. To my eyes it added nothing new and also seemed to miss the fact that Oman changed his opinion.
Do share what you find out, please. I agree that much of what is written about it parrots Oman's earlier article. Chandler, being a sound historian, was aware that Oman changed his opinion as he found new evidence. Regards,