@article{IonescuGreinerMuelleretal.2006, author = {Dorin Cezar Ionescu and Walter Greiner and Berndt M{\"u}ller and Gerhard Soff}, title = {Collective excitations of the QED vacuum}, journal = {Physical review A}, volume = {47}, number = {2}, pages = {854 -- 867}, year = {2006}, }