G. FLÜGEL: _Ueber Inhalt und Verfasser der arabischen Encyclopädie der Ikhwan as-Safa._ ZDMG, xiii, pp. 1 ff. See, too, an excellent article by August Müller in _Ersch und Gruber_, ii, 42, pp. 272 ff., and Stanley Lane-Poole in his _Studies in a Mosque_. FRIEDRICH DIETERICI: _Die Philosophie der Araber im X. Jahrhundert n. Chr. aus der Schriften der lauteren Brüder herausgegeben._ Berlin and Leipzig, 1861-1879. IGNAZ GOLDZIHER: _Materialien zur Entwickelungs-geschichte des Sufismus._ WZ, xiii, pp. 35 ff. THEODOR NÖLDEKE: _Sufi._ ZDMG, xlviii, pp. 45 ff. On the derivation and early usage of the name Sufi. ADELBERT MERX: _Idee und Grundlinien einer allgemeinen Geschichte der Mystik._ Heidelberg, 1893. JOHN P. BROWN: _The Derwishes or Oriental Spiritualism._ London, 1868. A valuable but uncritical description of modern Turkish and Persian Darwishes. SIR JAMES REDHOUSE: _The Mesnevi of Jelal eddin ar-rumi translated into English._ Book I. London, 1881. See, too, a translation by Whinfield, London, 1887, and an edition of selected ghazels from the Diwan with translation and valuable introduction by R. A. Nicholson, Cambridge University Press, 1898. E. J. W. GIBB: _A History of Ottoman Poetry._ Vol. i. London, 1900. A valuable statement of the later Persian and Turkish mysticism and metaphysic on pp. 13-70. E. H. PALMER: _Oriental Mysticism._ Cambridge, 1867. CARRA DE VAUX: _Avicenne._ Paris, 1900. Contains an introductory sketch of philosophy and theology up to the time of Ibn Sina. _Algazali._ Paris, 1902. A continuation of the first. A. VON KREMER: _Über die philosophischen Gedichte des Abul Ala Ma‘arry._ Wien, 1888. A. VON KREMER: _Gedichte des Abu-l-Ala Ma‘arri._ ZDMG, xxix, 304; xxx, 40; xxxi, pp. 471 ff.; xxxviii, 499 ff. ABU-L-ALA AL-MA‘ARRI: _Letters Arabic and English, with notes, etc., edited by D. S. Margoliouth._ Oxford, 1898. See, too, papers by R. A. Nicholson in JRAS, October, 1900, ff.; and by Margoliouth, for April, 1902. E. FITZGERALD: _The Ruba‘iyat of Omar Khayyam. With a commentary by H. M. Batson and a biographical Introduction by_ _E. D. Ross._ New York, 1900. The biography by Ross is the only at all adequate treatment of the life and times of Umar which yet exists. Of the Ruba‘iyat themselves there are several adequate translations, _e.g._ by Whinfield, Payne and Mrs. Cadell. MARTIN SCHREINER: _Zur Geschichte der Polemik zwischen Juden und Muhammedanern._ ZDMG, xlii, pp. 591 ff. Deals with Ibn Hazm and Fakhr ad-Din ar-Razi. MARTIN SCHREINER: _Beiträge zur Geschichte der theologischen Bewegungen in Islam._ ZDMG, lii, pp. 463 ff.; 513 ff.; liii, pp. 51 ff. A most valuable collection of materials with considerable gaps and imperfect digestion.