Burdekin, Richard C.K.; Langdana, Farrokh K. (July 1993), "War Finance in the Southern Confederacy, 1861-1865", Explorations in Economic History, 30 (3): 352–376, doi:10.1006/exeh.1993.1015. See in particular p. 357: "Congress felt compelled to approve the Tithe Act, or the "Tax-in-Kind," on April 24, 1863. This tax act of 1863, which was intended to remain in force until the end of 1865, supplemented a combined property tax and graded income tax with a tax-in-kind equal to one-tenth of the agricultural produce of 1863."
