Press Release: IAB / PWC Report $1.66 Billing Internet Ad Revenue for Q2 2003
Report: IAB Internet Advertising Revenue Report 2003 Q2 Results
Reuters: Online advertising spending still on the rise
WSJ (subscription required): Online-Ad Sales Continue Upswing

Second quarter online advertising spending rose 14 percent over the same period last year. Media vendors sold $1.66 billion dollars in Internet marketing inventory, as recorded by the IAB and PriceWaterhouseCoopers through public SEC filings that were then extrapolated across the rest of the industry.