The minutes from the 4/12/83 Saddle Club meeting. Note that the document does not say "1983" anywhere on it, but it refers to "Monday April 25th", and April 25th was a Monday in 1983. Additionally, it was in a pile of documents from 1983.
UMM Saddle Club, "Saddle Club 4/12/83 Meeting Minutes" (1983). Saddle Club. 82.