Robert G. Calkins, "Piero de' Crescenzi and the Medieval Garden", in Medieval Gardens, ed. Elisabeth B. MacDougall, Dumbarton Oaks, 1986: 155–173. Selected pages at Google Books
osu.edu
hcs.osu.edu
"Crescenzi, Pietro – 14th Century". History of Horticulture. The Ohio State University. Diarsipkan dari versi asli tanggal 2011-05-17. Diakses tanggal June 2011.Periksa nilai tanggal di: |accessdate= (bantuan)
web.archive.org
"Crescenzi, Pietro – 14th Century". History of Horticulture. The Ohio State University. Diarsipkan dari versi asli tanggal 2011-05-17. Diakses tanggal June 2011.Periksa nilai tanggal di: |accessdate= (bantuan)