Use of the Period After the "S" in Harry S. Truman's Name

"According to The Chicago Manual of Style all initials given with a name should "for convenience and consistency" be followed by a period even if they are not abbreviations of names. The U.S. Government Printing Office Style Manual states that the period should be used after the "S" in Harry S. Truman's name.

Most published works using the name Harry S. Truman employ the period. Authors choosing to omit the period in their texts must still use it when citing the names of organizations that employ the period in their legal titles... " 

See all at:

https://www.trumanlibrary.gov/education/trivia/use-of-period-after-s-truman-name