1.https://www.preventivevet.com/dogs/when-vomiting-isnt-actually-vomiting
2.http://www.dogster.com/dog-health-care/dog-vomiting
3.http://www.pethealthnetwork.com/dog-health/dog-diseases-conditions-a-z/my-dog-vomiting-or-regurgitating
4.http://veterinarymedicine.dvm360.com/recognizing-and-treating-esophageal-disorders-dogs-and-cats
5.http://criticalcaredvm.com/the-dreaded-megaesophagus
6.https://vcahospitals.com/know-your-pet/megaesophagus
7.https://www.petmd.com/dog/conditions/digestive/c_dg_megaesophagus
8.https://www.medicinenet.com/pets/dog-health/dog_is_regurgitating_his_food.htm
9.http://www.petwave.com/Dogs/Health/Gastrointestinal-Obstruction/Symptoms.aspx
10.https://vcahospitals.com/know-your-pet/slippery-elm
11.http://www.akc.org/content/health/articles/dog-vomiting-causes-diagnosis-and-treatment
12.http://www.dogster.com/dog-health-care/dog-vomiting-blood-what-to-do