Recently, an agile software development technique called extreme programming has caught the attention of practitioners and researchers in the software industry. A core practice of extreme programming is pair programming, where two developers work on the same piece of code. We introduce the...

The accumulated evidence indicates that pure revenue models, such as free-access models and pure subscription fee-based models, are not sufficient to support the survival of online information sellers. Hence, hybrid models based on a combination of subscription fees and advertising revenues are...