Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.
Incentive-based link requests use an incentive as part of the process of requesting a link. This can run dangerously close to violating the search engines’ Webmaster Guidelines, but there are also ways to do it that remain compliant with those guidelines.
Content syndication can be a powerful tactic, and we will cover this in more detail in More Approaches to Content-Based Link Acquisition. The concept is to develop content with the intent of publishing it on third-party sites. The site that is publishing the content provides a link back to your site in return for being permitted to publish the content. Ideally, this content should be distinct from the content on your own site to avoid any risk of duplicate content issues.