Supplemental Agreements (1961 - Current)
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ISP
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Current:
Supplemental Agreements (1961 - Current)
- July 1, 1959
- January 1, 1961
- July 1, 1966
- August 1, 1968
- July 1, 1971
- March 15, 1985
- May 1, 1989
- July 1, 1991
- July 1, 2001
- September 1, 2002
- September 1, 2002; Conformed November 14, 2007
- January 1, 2009
- January 1, 2014
- January 1, 2023
