The citation form used for a federal regulation is: Title/Number, Volume Source § xxx (year).
Newborn children, 42 C.F.R. § 435.117 (2012).
Medicaid program; eligibility changes under the Affordable Care Act of 2010. 77 Fed. Reg. 17143 (Final rule, Interim final rule Mar. 23, 2012) (to be codified at 42 C.F.R. pt. 431, 435 and 457).
Newborn children (2012)
(Medicaid program; eligibility changes under the Affordable Care Act of 2010, 2012)
See the Publication Manual of the American Psychological Association (6th edition), Appendix A7.06 - Administrative and Executive Materials for more information.