The IRS has published the reference price under Code Sec. 45K(d)(2)(C). The credit period for the nonconventional source production credit under Code Sec. 45K ended on December 31, 2013, for facilities producing coke or coke gas (other than from petroleum based products). However, the reference price continues to apply in determining the amount of the enhanced oil recovery credit under Code Sec. 43, the marginal well production credit for qualified crude oil production under Code Sec. 45I, and the percentage depletion in case of oil and natural gas produced from marginal properties under Code Sec. 613A. The reference price for calendar year 2018 is $61.41.