- COBR : John A. O'Brien: Manuscripts
- COBR 1-5/ Series : Correspondence 1920-1974
- COBR 1-2/ Subseries : General Correspondence 1920-1974
- COBR 1/00 Folder : General Correspondence - Anti-Catholic Writings c1950-1960
- COBR 1/01-02 Group : General Correspondence - A 1947-1974
- COBR 1/03 Folder : Bostrom, Harold W.- Milwaukee
- COBR 1/04 Folder : General Correspondence - B 1964-1974
- COBR 1/05 Folder : General Correspondence - B 1920-1953
- COBR 1/06 Folder : Bunnik, Rev. R.J.
- COBR 1/07 Folder : General Correspondence - C 1925-1952
- COBR 1/08 Folder : General Correspondence - C 1958-1970
- COBR 1/09 Folder : General Correspondence - C 1949-1974
- COBR 1/10 Folder : Canfield, Cass - New York
- COBR 1/11 Folder : Celibacy - Pro Letters 1967-1973
- COBR 1/12 Folder : Charts c1946
- COBR 1/13 Folder : Circular Letters 1943
- COBR 1/14 Folder : Cody, John Cardinal - Chicago
- COBR 1/15 Folder : Converts 1948
- COBR 1/16 Folder : Correspondence - Unidentified 1931-1943
- COBR 1/17 Folder : General Correspondence - D 1962-1974
- COBR 1/18 Folder : General Correspondence - D 1926-1946
- COBR 1/19 Folder : General Correspondence - E 1944-1951
- COBR 1/20 Folder : General Correspondence - E 1964-1974
- COBR 1/21 Folder : Evolution 1926-1949
- COBR 1/22 Folder : General Correspondence - F 1943-1949
- COBR 1/23 Folder : General Correspondence - F 1971-1974
- COBR 1/24 Folder : General Correspondence - G 1935-1950
- COBR 1/25 Folder : General Correspondence - G 1961-1973
- COBR 1/26 Folder : General Correspondence - H 1922-1950
- COBR 1/27 Folder : General Correspondence - H 1970-1973
- COBR 1/28 Folder : Henry, Harold W., Bp.- Kwangju 1961-1971
- COBR 1/29 Folder : Hesburgh, Theodore - Notre Dame 1959-1972
- COBR 1/30 Folder : Hostile Literature 1972
- COBR 1/31 Folder : General Correspondence - I 1961-1974
- COBR 1/32 Folder : Imprimatur - Nihil Obstat 1946-1955
- COBR 1/33 Folder : General Correspondence - J 1940-1945
- COBR 1/34 Folder : General Correspondence - J 1962-1974
- COBR 1/35 Folder : Jehovah's Witness 1942-1947
- COBR 1/36 Folder : General Correspondence - K 1964-1974
- COBR 1/37 Folder : General Correspondence - K 1935-1945
- COBR 1/38 Folder : Kennedy, John F. 1960-1969
- COBR 1/39 Folder : General Correspondence - L 1950-1974
- COBR 1/40 Folder : General Correspondence - L 1943-1973
- COBR 1/41 Folder : Laetare Medal 1973
- COBR 1/42 Folder : Lectures 1967-1974
- COBR 1/43 Folder : Libraries 1960-1974
- COBR 1/44 Folder : General Correspondence - M 1956-1974
- COBR 1/45 Folder : General Correspondence - M 1940-1945
- COBR 1/46 Folder : General Correspondence - M 1931-1954
- COBR 1/47 Folder : Martyrs 1949
- COBR 1/48 Folder : May, Mrs. Orville - Marietta 1962-1967
- COBR 1/49 Folder : General Correspondence - Mc 1970-1974
- COBR 1/50 Folder : McNeill, Leon A., Msgr.- Wichita 1965-1968
- COBR 1/51 Folder : General Correspondence - N 1932-1945
- COBR 1/52 Folder : General Correspondence - N 1965-1972
- COBR 1/53 Folder : NBC - National Broadcasting Company 1962-1970
- COBR 1/54 Folder : Newsweek - New York 1959-1970
- COBR 1/55 Folder : Notre Dame 1937-1946
- COBR 1/56 Folder : Notre Dame 1946-1957
- COBR 1/57 Folder : Notre Dame 1968-1974
- COBR 1/58 Folder : General Correspondence - O 1932-1956
- COBR 1/59 Folder : General Correspondence - O 1954-1974
- COBR 1/60 Folder : Opinion Institute 1961
- COBR 1/61 Folder : General Correspondence - P 1932-1971
- COBR 1/62 Folder : General Correspondence - P 1960-1973
- COBR 1/63 Folder : Pamphlet Distributors 1948
- COBR 1/64 Folder : Psychiatry 1948
- COBR 1/65 Folder : Pursley, Leo A., Bp.- Fort Wayne 1955-1973
- COBR 2/01 Folder : General Correspondence - Q 1971
- COBR 2/02 Folder : General Correspondence - R 1953-1973
- COBR 2/03 Folder : General Correspondence - R 1938-1948
- COBR 2/04 Folder : Raymon, Wilda Marshall - Crystal Lake 1967-1972
- COBR 2/05 Folder : Roberts, Thomas D., Bp.- London 1969-1971
- COBR 2/06 Folder : General Correspondence - S 1930-1956
- COBR 2/07 Folder : General Correspondence - S 1952-1974
- COBR 2/08 Folder : Scharpen, Gertrude - Inglewood 1963-1972
- COBR 2/09 Folder : Scholars and Schools 1946-1947
- COBR 2/10 Folder : Shannon, James P. 1969-1970
- COBR 2/11 Folder : Sisters 1946-1956
- COBR 2/12 Folder : Stone, W. Clement - Evanston, Chicago 1964-1974
- COBR 2/13 Folder : Suenens, Leo Cardinal - Malines 1965-1972
- COBR 2/14 Folder : General Correspondence - T 1934-1949
- COBR 2/15 Folder : General Correspondence - T 1960-1974
- COBR 2/16 Folder : Time Magazine - New York 1960-1971
- COBR 2/17 Folder : General Correspondence - U 1944-1947
- COBR 2/18 Folder : General Correspondence - U 1970
- COBR 2/19 Folder : Ueberall, Esther - Peekskill 1959-1973
- COBR 2/20 Folder : General Correspondence - V 1934-1948
- COBR 2/21 Folder : General Correspondence - V 1952-1974
- COBR 2/22 Folder : General Correspondence - W 1943-1948
- COBR 2/23 Folder : General Correspondence - W 1954-1974
- COBR 2/24 Folder : Wall, Mrs. Lucius and Sullivan 1965-1974
- COBR 2/25 Folder : General Correspondence - X-Y 1953
- COBR 2/26 Folder : General Correspondence - Y 1944
- COBR 2/27 Folder : General Correspondence - Z 1945
- COBR 2/28 Folder : General Correspondence - Z 1971
- COBR 2-4/ Subseries : Publications Correspondence
- COBR 2/29 Folder : Abbey Press 1965-1974
- COBR 2/30 Folder : Abingdon Press 1969-1970