“Freeze-Form Extrusion Fabrication of Functionally Graded Materials,” M. C. Leu, B. K. Deuser, L. Tang, R. G. Landers, G. E. Hilmas, and J. L. Watts, Proceedings of the 23rd Annual International Solid Freeform Fabrication Symposium -- An Additive Manufacturing Conference (2012, Austin, TX), pp. 467-479, University of Texas at Austin, Aug 2012.