Ṭuruq and ṭuruq-linked institutions by Frederick De Jong was first published in 1978. It is largely based on research in public and private archives in Cairo, and on published materials in limited circulation. This study became highly influential in its field. De Jong describes the development of the administration and organization of the ṭuruq and ṭuruq-linked institutions (takāyā, zawāyā, and shrines) under the shaykhs of the Bakrī family in nineteenth- and early twentieth-century Egypt. Central to this administration is the principle of right of qadam, meaning the exclusive right of a ṭarīqa to proselytize and to appear in public in a particular area, if it could be proved that it had been the first to do so.