@article{White2011,
    author = {P. J. White and S. Revzen and C. E. Thorne and M. Yim},
    title = {A General Stiffness Model for Programmable Matter and Modular Robotic Structures},
    journal = {Robotica},
    volume = {29},
    number = {Special Issue 01},
    pages = {103-121},
    year = {2011}
}