Of general works dealing with the questions I have touched, the following, to which I owe a considerable debt, may be recommended:—
J. Goldziher. Muhammedanische Studien, Halle, 1889 and following
year.
Die Religion des Islams (Kult. d. Gegenw., I, iii. 1).
C. Snouck Hurgronje. De Islam (de Gids, 1886, us. 5 f.).
Mekka. The Hague, 1888.
Une nouvelle biographie de Mohammed (Rev. Hist. Relig., 1894).
Leone Caetani di Teano. Annali dell' Islam. Milan, 1905 and following years.
F. Buhl. Muhammed's Liv. Copenhagen, 1903.
H. Grimme. Muhammed. Munich, 1904.
J. Wellhausen. Das arabische Reich und sein Sturz. Berlin, 1902.
Th. Nöldeke. Geschichte des Qoräns. Gottingen, 1860. (New edition by
F. Schwally in the press.)