Smith BT, Bittner SM, Watson E, Smoak MM, Diaz-Gomez L, Molina ER, Kim YS, Hudgins CD, Melchiorri AJ, Scott DW, Grande-Allen KJ, Yoo JJ, Atala A, Fisher JP, Mikos AG. Multimaterial Dual Gradient Three-Dimensional Printing for Osteogenic Differentiation and Spatial Segregation. Tissue Eng Part A. 2020 03; 26(5-6):239-252.