TITLE: Who originated the standard symbols for Lie groups GL, SL, SU, etc.?
QUESTION [19 upvotes]: Who was first to use symbols GL, SL, O, SO, U, SU, Sp and their projective versions, and how did this notation become standard?
The notation appears in fairly modern form in Weyl's "The Classical Groups" except that he uses $O^+$ for SO. I know that Weyl coined the term "symplectic group", so the notation Sp certainly originates with him.
Can anyone confirm or deny that Weyl was the originator of the standard symbols for Lie groups?
Thanks.

REPLY [14 votes]: In his 1939 book Weyl indeed did not use the notation SO but $O^+$, and called it the proper orthogonal group, but he did use the notation SU, or more precisely $^s$U with a tiny superscript s.

The name "special unitary group" does not appear, it is always "unimodular".
The footnote on the name "symplectic group", from the same book, is amusing: