Columbia subject headings:
Boole, George, 1815-1864.
De Morgan, Augustus, 1806-1871.
Logic, Symbolic and mathematical.
Logicians--Correspondence.
Harvard subject headings:
Boole, George, 1815-1864.
De Morgan, Augustus, 1806-1871.
Logic, Symbolic and mathematical.
Logicians--Correspondence.
Princeton subject headings:
Boole, George, 1815-1864.
De Morgan, Augustus, 1806-1871.
Logicians--Correspondence.
Mathematicians--Correspondence.