TY - JOUR PB - American Physical Society ID - 10.1103/Physics.4.7 TI - A useful pyramid scheme JF - Physics JA - Physics J1 - PHYSICS VL - 4 IS - SP - 7 EP - PY - 2011/01/24/ UR - http://link.aps.org/doi/10.1103/Physics.4.7 A1 - Cava, Robert J. ER -