Tarek Sayed Ahmed Basim Samir The Class <i>S</i>Nr<sub>3</sub>CA<sub><i>k</i></sub> is Not Closed Under Completions. 427-429 2008 16 Logic Journal of the IGPL 5 http://dx.doi.org/10.1093/jigpal/jzn019 db/journals/igpl/igpl16.html#AhmedS08