[A] The notes to which this and the other "superior figures" invite attention will be found immediately after the text of the volume. In the notes only brief titles of books are given, but these may be supplemented by reference to the list of printed sources given in the appendix of the second volume. Citations (in the notes) preceded by a number in black type refer to the list of MS. sources standing at the end of the notes. The warrant for offering another work on the subject rests primarily on the extent and results of the author's investigations. His intention was to obtain substantially all the valuable information regarding it that is in existence, and no effort was spared to reach his end. The appendix of volume II gives a detailed account of the sources. By special authorization from the Presidents of the United States and Mexico it was possible to examine every pertinent document belonging to the two governments. The search extended to the archives of Great Britain, France, Spain, Cuba, Colombia and Peru, those of the American and Mexican states, and those of Mexican cities. The principal libraries here, in Mexico and in Europe, the collections of our historical societies, and papers belonging to many individuals in this country and elsewhere were sifted. It may safely be estimated that the author examined personally more than 100,000 manuscripts bearing upon the subject, more than 1200 books and pamphlets, and also more than 200 periodicals, the most important of which were studied, issue by issue, for the entire period.[B] Almost exclusively the book is based upon first-hand sources, printed matter having been found of little use except for the original material it contains or for data regarding biography, geography, customs, industries and other ancillary subjects.[P.2] [B] These figures cover also the author's "Annexation of Texas," which is virtually an introduction to the present work. The author also talked or corresponded with as many of the veterans as he could reach, and he spent more than a year, all told, in Mexico, where he not only studied the chief battlefields but endeavored, through conversations with Mexicans of all grades and by the aid of foreigners long resident in the country, to become well acquainted with the character and psychology of the people. As the war was fought almost exclusively among them, and its inception, course and results depended in large part upon these factors, the author attaches not a little importance to his opportunities for such personal investigations and to his Mexican data in general.[P.2]