Rabbi Schneur Zalman of Liadi, founder of the Chabad-Lubavitch Movement, established a unique method by which to sell ones chometz before Pesach, and published it in his Siddur. Seder Mechiras Chometz presents the text of Rabbi Schneur Zalmans method, with copious commentary and annotations by Rabbi Sholom DovBer Levine. (These are the laws of selling leavened products and foods before Passover.)