The Ocarina septet - History of an Italian tradition is so far, in my opinion, the only serious, scientifically-written book on ocarina history and tradition - every piece of information that is presented in the book is extensively referenced in bibliography. Most other books I've seen on ocarina history mix facts and legends (to some degree), often neglecting to cite sources.
The book is divided into five chapters:
- Le origini dell'ocarina di Budrio - The first chapter documents the invention of the ocarina in the year 1853 in Budrio, from the first toys and experimental mid-stages to complete music instruments of the current form and with full chromatic range. Contains written accounts by G. Donati and A. N. Mezzetti (two men mostly responsible for the invention of the ocarina) and others.
- L'ocarina nel mondo - Documents the development of the ocarina in the 20th and 21st outside Budrio, focusing mostly on oriental ocarina culture, but also on ocarinas in America and elsewhere.
- I complessi ocarinistici a Budrio - The third chapter presents the history of ocarina groups in Budrio, beginning from 1863 until today, citing newspaper articles and commentaries. It also contains an article about the ocarina school in Budrio.
- I repertori e le musiche - This chapter speaks about the music for the ocarina, in particular for the ocarina septet - the classical music repertoire and popular repertoire. It addresses playing techniques on the ocarina, possibilities of the instrument and how music is arranged for the ocarina septet and speaks about the most important arrangers of music for the ocarina, such as Cesare Testi, Giuseppe Grossi, Alfredo Barattoni and Emiliano Bernagozzi.
- La construzione di ocarine a Budrio - The last chapter documents the process of the construction of the ocarina, about materials, techniques and phases in construction. It also contains short biographies of the 7 ocarina makers from Budrio: Donati, the Mezzetti brothers, Vicinelli, Chiesa, Cesari, Mignani and Menaglio.
SuperBobKing wrote:
What does it contain as far as history goes? Does it have any preference towards performing, making, or the instruments themselves? Also, how in depth does it go into each of those subjects?
One would tend to assume that a relatively small book such as this one, having less than 150 pages, with illustrations on practically every page, would be lacking in content. However, in this case, such assumption would be completely wrong - this book is very thoroughly written, encompassing details of all the subjects you mentioned. Keep in mind though, this book is none of the following: a method book for the ocarina, an ocarina maker's manual, a composer's or music arranger's guide, a catalogue of an ocarina collection... Instead, it is a book that documents (with bibliographical references) the Italian tradition and the culture of ocarina, in all of its aspects, and that it does excellently.
The accompanying CD contains contemporary classical music for the ocarina performed by Gruppo Ocarinistico Budriese, and while some of the more original pieces on it are not particularly suited to my personal taste (I'm not a big fan of atonal music, for example), there are a few tracks that are incredibly beautiful, for example, Stefano Franceschini's Rondini. And, of course, the standard of performance is GOB quality, in my opinion unmatched by any other ocarina group. 
In conclusion, I wholeheartedly recommend this book to anyone with interest in the ocarina.