I defended my PhD thesis at the University of Geneva on 20 March 1975. My supervisors were Prof. H. Ruegg (University of Geneva) and Prof. C. Itzykson (Centre de Physique Theorique de Saclay, Paris). Since then I held different positions at the university and at the Spanish Council for Scientific Research (CSIC). In particular before my ICREA position I tenured a Research Professorship at the "Instituto de Estructura de la Materia", Madrid (CSIC). During my scientific career I have got in contact with many researchers and Research Centers worldwide. I have been Invited Professor and/or Guest Scientist at: CERN (Geneva), Fermilab (USA), Université de Pierre et Marie Curie, École Normale Superieure, Université d'Orsay and Ecole Polytechnique (Paris, France), University of Padua (Italy), International Centre for Theoretical Physics in Trieste (Italy and Sao Paulo), University of Ann Arbor (USA), University of California at Santa Cruz (USA), University of Notre Dame (USA), etc.