Fisichella, P. Marco; Patti, Marco G. (October 2014). "From Heller to POEM (1914-2014): a 100-year history of surgery for Achalasia". Journal of Gastrointestinal Surgery. 18 (10): 1870–1875. doi:10.1007/s11605-014-2547-8. ISSN1873-4626. PMID24878993. S2CID1290385.
Fisichella, P. Marco; Patti, Marco G. (October 2014). "From Heller to POEM (1914-2014): a 100-year history of surgery for Achalasia". Journal of Gastrointestinal Surgery. 18 (10): 1870–1875. doi:10.1007/s11605-014-2547-8. ISSN1873-4626. PMID24878993. S2CID1290385.
Fisichella, P. Marco; Patti, Marco G. (October 2014). "From Heller to POEM (1914-2014): a 100-year history of surgery for Achalasia". Journal of Gastrointestinal Surgery. 18 (10): 1870–1875. doi:10.1007/s11605-014-2547-8. ISSN1873-4626. PMID24878993. S2CID1290385.
Fisichella, P. Marco; Patti, Marco G. (October 2014). "From Heller to POEM (1914-2014): a 100-year history of surgery for Achalasia". Journal of Gastrointestinal Surgery. 18 (10): 1870–1875. doi:10.1007/s11605-014-2547-8. ISSN1873-4626. PMID24878993. S2CID1290385.