This article explains the Virtual Reference Desk for mathematics realized by Antonella De Robbio, during her time of working at the library of CERN (European Laboratory for Particle Physics – Laboratoire européen pour la physique des particules) in Geneva (Switzerland).
This web meta-resource is organized into three parts with two specific aims: 
1. a work tool for librarians which are involved in mathematics libraries  but also for users that need resources about particle physics;
2. web resources specialized in mathematics only, in particular for mathematicians of the university of Padua (Italy), where Antonella De Robbio worked in for about twenty years.
These two aims are based on a point of view both mathematics and physics subjects as well as librarian skills. 
To sum up, this VRD collects training and professional materials but also new and current online resources available nowadays.