What Gioia does is select some 250-plus pieces that have been played so often by such a broad range of musicians that they may be defined as "standards."
Besides being an historian, Gioia is also a teacher, and he uses this ability to his, and our, advantage. His prose is friendly and never pedantic. Gioia's knowledge of his subject is vast, particularly considering that he provides multiple recording recommendations for each song and, in particular, his "track reviews" where he selects a specific performance and analyzes it. Gioia proves a master at providing context for these famous songs. His technical explanations are never too technical and always easy to understand.
And see also the review at the LA Times. (Thanks: CW.)