How Viagra Made Pfizer Billions Before Generics

Generic Viagra floods the market. Here's how Pfizer is reacting - Marketplace

How Pfizer Is Coping with Generic Competition for Viagra

Why Pfizer's Viagra Now Costs Half as Much

Pfizer Inc. Stock Desperately Needs a Viagra-Like Boost

Viagra: A Complicated Case Study of Generic Drug Market Entry in the United States – DrugPatentWatch - Make Better Decisions

How Viagra was discovered by Pfizer

Pfizer hikes cost of Viagra and 100 other drugs, report says

Viagra: The little blue pill that could

Mylan merger with Pfizer's Upjohn unit to form new company with $20 billion in revenues