I understand you're looking for information on the by Welles Wilder , and specifically a PDF download. However, I must provide some important context first. What is the Delta Phenomenon? The Delta Phenomenon is a trading theory developed by Welles Wilder (famous for technical indicators like RSI, DMI, and Parabolic SAR) and Jim Sloman . It was published in a proprietary book in 1991. The theory proposes that many financial markets (and even natural phenomena) move in repetitive, time-based cycles or "turning points" that align with specific intervals of the solar/lunar calendar.