Stock-Allen, Nancy (2016-01-01). Carol Twombly her brief but brilliant career in type design. New Castle, Delaware: Oak Knoll Press. pp. 75–77. ISBN9781584563464. OCLC962730154.
Stock-Allen, Nancy (2016-01-01). Carol Twombly her brief but brilliant career in type design. New Castle, Delaware: Oak Knoll Press. p. 79. ISBN9781584563464. OCLC962730154.
Stock-Allen, Nancy (2016-01-01). Carol Twombly her brief but brilliant career in type design. New Castle, Delaware: Oak Knoll Press. p. 84. ISBN9781584563464. OCLC962730154.
Stock-Allen, Nancy (2016-01-01). Carol Twombly her brief but brilliant career in type design. New Castle, Delaware: Oak Knoll Press. pp. 88–96. ISBN9781584563464. OCLC962730154.
Stock-Allen, Nancy (2016-01-01). Carol Twombly her brief but brilliant career in type design. New Castle, Delaware: Oak Knoll Press. pp. 101–105. ISBN9781584563464. OCLC962730154.
Stock-Allen, Nancy (2016-01-01). Carol Twombly her brief but brilliant career in type design. New Castle, Delaware: Oak Knoll Press. p. 113. ISBN9781584563464. OCLC962730154.
Stock-Allen, Nancy (2016-01-01). Carol Twombly her brief but brilliant career in type design. New Castle, Delaware: Oak Knoll Press. pp. 117–120. ISBN9781584563464. OCLC962730154.
Stock-Allen, Nancy (2016-01-01). Carol Twombly her brief but brilliant career in type design. New Castle, Delaware: Oak Knoll Press. p. 135. ISBN9781584563464. OCLC962730154.