Written bylaws from when professional base ball was formed:
1876
https://ourgame.mlblogs.com/constitution-and-playing-rules-of-the-national-league-of-professional-base-ball-clubs-b79ee1eef3b3
1887
https://archive.org/details/ConstitutionAndPlayingRulesOfTheNationalLeague1886
1888
https://library.si.edu/digital-library/book/spaldingquotsba1888