Partial paywall similar to 'First Click Free' After experimenting with a "free to air" traffic model for the past year, http://www.scientificamerican.com will be putting all magazine features (with a few exceptions) back behind a pay wall. This includes the September 2009 issue, which launches on the site on August 17th, and all issues dating back to January 2001. Only Scientific American Digital (http://www.sciamdigital.com) subscribers and single-issue purchasers will have full access to the magazine features (in PDF format). All other visitors to the feature articles will see a brief sampling of the article and will be encouraged to subscribe or make a single issue purchase. We would like to give free html access to paid magazine feature content to visitors that are entering these pages directly from certain external referral sources - including Google and other search engines/key sites. The plan is to give 1 free viewing to users who enter the site directly through a paid magazine feature page. If the user clicks through to another paid magazine feature, they will see the same article preview that other users will view. Can anyone comment on whether this is an acceptable practice for ScientificAmerican.com that won't result in penalization of any sort. We accept that showing short content summaries together with the 'subscribe now to read the rest of this article' link will probaby result in less traffic but we are prepared for this.