Cunningham, Joseph; DeHart, Leonard O. (January 1, 1993). A History of the New York City Subway System. J. Schmidt, R. Giglio, and K. Lang. Archived from the original on May 2, 2022. Retrieved December 30, 2020.
Linder, Bernard (February 2016). "Contract 4 Subway Controversy". The Bulletin. Vol. 59, no. 2. Electric Railroaders' Association. pp. 1, 6. Archived from the original on August 16, 2016. Retrieved July 28, 2016.
"Have Obtained Valuable Rights: Public Service Gets Free Many Station Entrances on New Routes". New-York Tribune. July 11, 1915. p. C2. ISSN1941-0646. ProQuest575403970.
Harrington, John Walker (May 17, 1931). "Nassau St. Loop In Subway Opens Memorial Day: Link for 3 Divisions, Costing 11 Millions a Mile, to Speed Service 40 P. C. Task Debated 18 Years 4-Track System in Broad St. Part of Switching Plan Scenes and Charts in Forging of City's New Underground Railway Link". New York Herald Tribune. p. A12. ISSN1941-0646. ProQuest1114183895.
"Mayor Inspects New Nassau St. Subway Today: City Officials To Be Guests of B.M.T. in Tour of Links That Open Tomorrow". New York Herald Tribune. May 29, 1931. p. 21. ISSN1941-0646. ProQuest1114186438.
"Walker Operates First Train in Nassau St. Loop: Tests Out Whistle Before Sudden Stop for Which Instructor Takes Blame New B. M. T. System Link Other Officials at Opening of $10,000,000 Subway Nassau Street Subway Is Formally Opened". New York Herald Tribune. May 30, 1931. p. 3. ISSN1941-0646. ProQuest1114103146.
"Nassau-Broad Subway Route Opens May 30: 14th St. Link of B. M. T. Line From 6th to 8th Aves. Also To Be Finished Then Both Cost $13,630,313 City Labored Three Years on Engineering Projects". New York Herald Tribune. May 10, 1931. p. 2. ISSN1941-0646. ProQuest1114181918.
"B.M.T. Provides Through Service On Culver Line: Additional Trains on Nassau St. Loop and 14th St. Extension Run May 30". New York Herald Tribune. May 21, 1931. p. 43. ISSN1941-0646. ProQuest1114100391.
Linder, Bernard (February 2016). "Contract 4 Subway Controversy". The Bulletin. Vol. 59, no. 2. Electric Railroaders' Association. pp. 1, 6. Archived from the original on August 16, 2016. Retrieved July 28, 2016.
Cunningham, Joseph; DeHart, Leonard O. (January 1, 1993). A History of the New York City Subway System. J. Schmidt, R. Giglio, and K. Lang. Archived from the original on May 2, 2022. Retrieved December 30, 2020.
"Have Obtained Valuable Rights: Public Service Gets Free Many Station Entrances on New Routes". New-York Tribune. July 11, 1915. p. C2. ISSN1941-0646. ProQuest575403970.
Harrington, John Walker (May 17, 1931). "Nassau St. Loop In Subway Opens Memorial Day: Link for 3 Divisions, Costing 11 Millions a Mile, to Speed Service 40 P. C. Task Debated 18 Years 4-Track System in Broad St. Part of Switching Plan Scenes and Charts in Forging of City's New Underground Railway Link". New York Herald Tribune. p. A12. ISSN1941-0646. ProQuest1114183895.
"Mayor Inspects New Nassau St. Subway Today: City Officials To Be Guests of B.M.T. in Tour of Links That Open Tomorrow". New York Herald Tribune. May 29, 1931. p. 21. ISSN1941-0646. ProQuest1114186438.
"Walker Operates First Train in Nassau St. Loop: Tests Out Whistle Before Sudden Stop for Which Instructor Takes Blame New B. M. T. System Link Other Officials at Opening of $10,000,000 Subway Nassau Street Subway Is Formally Opened". New York Herald Tribune. May 30, 1931. p. 3. ISSN1941-0646. ProQuest1114103146.
"Nassau-Broad Subway Route Opens May 30: 14th St. Link of B. M. T. Line From 6th to 8th Aves. Also To Be Finished Then Both Cost $13,630,313 City Labored Three Years on Engineering Projects". New York Herald Tribune. May 10, 1931. p. 2. ISSN1941-0646. ProQuest1114181918.
"B.M.T. Provides Through Service On Culver Line: Additional Trains on Nassau St. Loop and 14th St. Extension Run May 30". New York Herald Tribune. May 21, 1931. p. 43. ISSN1941-0646. ProQuest1114100391.