By the number. Largest U.S. per diem nurse staffing firms. Ranked by estimated 2010 U.S. temporary staffing revenue ($ millions).
D004465:Economic Competition / Q000145:classification* / Q000191:economics; D006801:Humans; D009740:Nursing Staff / Q000191:economics / Q000600:supply & distribution*; D020416:Outsourced Services / Q000191:economics*; D010561:Personnel Staffing and Scheduling / Q000191:economics* / Q000458:organization & administration; D014481:United States