Oh, thank you...
I'm mostly familiar with European and especially German shootings.
The Jokela, Kauhajoki and Emsdetten shootings apparently were inspired by earlier shootings. The Winnenden shooting less so, though the Alabama shooting a day before might have been a trigger.
The Erfurt shooting certainly seemed to have been on the mind when Winnenden and Emsdetten happened. School shooters seem to have exactly the same cultish following as serial killers. There seems to be an appeal to young men. The perpertrators get stylised into "the last true outlaws".
What I found somewhat remarkable is that most German shootings had a higher number of female victims. Female teachers are more prevalent and yet Winnenden mostly targeted female pupils. I'm not sure if it actually means anything and if so what.