Hern, Mary Ellen W. (1989). "Picnicking in the Northeastern United States, 1840–1900". Winterthur Portfolio. Quyển 24 số 2/3. tr. 139–152. doi:10.1086/496417. JSTOR1181262.
Hern, Mary Ellen W. (1989). "Picnicking in the Northeastern United States, 1840–1900". Winterthur Portfolio. Quyển 24 số 2/3. tr. 139–152. doi:10.1086/496417. JSTOR1181262.
Hern, Mary Ellen W. (1989). "Picnicking in the Northeastern United States, 1840–1900". Winterthur Portfolio. Quyển 24 số 2/3. tr. 139–152. doi:10.1086/496417. JSTOR1181262.
Hern, Mary Ellen W. (1989). "Picnicking in the Northeastern United States, 1840–1900". Winterthur Portfolio. Quyển 24 số 2/3. tr. 139–152. doi:10.1086/496417. JSTOR1181262.