Conkling, R. P., & Conkling, M. B. (1947). The Butterfield Overland Mail, 1857-1869: Its organization and operation over the southern route to 1861; subsequently over the central route to 1866; and under Wells, Fargo and Company in 1869. A.H. Clark Co..
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Conkling, Roscoe P., و Margaret B. Conkling. The Butterfield Overland Mail, 1857-1869: Its Organization and Operation over the Southern Route to 1861; Subsequently over the Central Route to 1866; and Under Wells, Fargo and Company in 1869. Glendale, Calif.: A.H. Clark Co., 1947.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Conkling, Roscoe P., و Margaret B. Conkling. The Butterfield Overland Mail, 1857-1869: Its Organization and Operation over the Southern Route to 1861; Subsequently over the Central Route to 1866; and Under Wells, Fargo and Company in 1869. A.H. Clark Co., 1947.