From your textbook:

• Pro Athletes as Company Men (MSWord):  A more complete presentation of the excerpt in your book.
• The Curt Flood Act, 1998 (PDF):  The act giving baseball players the same rights as other athletes regarding antitrust and individual rights to sue.

Labor Relations Links, Current Topics:

• NHL Collective Bargaining Agreement, 2005 (PDF).
• NFL Collective Bargaining Agreement, 2006-2012 (PDF).
• MLB Arbitration List and Free Agents List:  From Doug Pappas Business of Baseball pages.  Hit the "Data Downloads" link.  Pappas' FREE AGENT FILINGS, 1974-2003.
• MLB Collective Bargaining Agreement, 2007-2011:  Discussion at MLB.com; Get the last CBAs since 1970 (PDF documents):  1970, 1976, 1990-1993, 1997-2000(2001), 2002-2006, 2007-2011.
• Salary Cap Details in the NFL and NBA (MSWord):  It's not as difficult to calculate as you might think.
• NBA 2005-2011 CBA:  View it at the NBPA page.  The previous agreement, 1999-2004, is here (PDF).
• NHL Free Agency Rules (MSWord):  As Byzantine as they come.
• The Levitt Report, 2004 (PDF):  Commissioned by NHL owners, former SEC Chairman Arthur Levitt documents massive losses in hockey just before the lockout of 2004.
• NFL Salary Cap Determination, 2004 (MSWord):  The actual formula used to figure the cap and the formula that determines how much a player counts under the cap.  Interesting and complex.

Don't forget that all of the salary and payroll data are at the Sports Business Data Pages!