The book The Sabbatian Movement and Its Aftermath: Messianism, Sabbatianism and Frankism, edited by Rachel Elior, is available online, in its entirety, for free (see here).

The book includes articles by Elisheva Carlebach, “The Sabbatian Posture of German Jewry,” Jacob J. Schacter, “Motivations for Radical Anti-Sabbatiansim: The Case of Hakham Zevi Ashkenazi,” as well as an excellent article in Hebrew by Moshe Fogal “Sabbatianism of the book Hemdat Yamim: A New Exploration.”