Cite the VisualDx topic as a chapter in an electronic book titled VisualDx with editor Lowell A. Goldsmith. There are no page numbers and publication year should be the current year.
EXAMPLE:
Papier A, Craft N, Tharp MD, Shear N. Cocaine Levamisole Toxicity. In: Goldsmith LA, ed. VisualDx. Rochester, NY: VisualDx; 2016. URL: //visualdx/visualdx6/getDiagnosisText.do?moduleId=14&diagnosisId=54687&view=text. Accessed January 1, 2016.