1940 Julian Coolidge in A History of Geometrical Methods , page 261 , uses the coordinate - free methods of Hamilton 's operators .
1940 Julian Coolidge in A History of Geometrical Methods , page 261 , cites A.L. Lawrence 's work at Harvard .
1940 Julian Coolidge in A History of Geometrical Methods , page 261 , uses the coordinate - free methods of Hamilton 's operators and cites A.L. Lawrence 's work at Harvard .