37 AUTOGRAPHED PHOTOGRAPHS AND POSTCARDS OF OPERA SINGERS, 1960s - 1970s Including 2 signed by Maria Callas (1923-1977), Gustave Botiaux (B.1926), Mady Mesplé (1931-2020), Giorgio Merighi (1939-2020), Isabel Strauss (1928-1973), Michel Dens (1911-2000) and more