Congratulations to Professor Domingos Moreira Cardoso on the occasion of his 65th birthday
I met Professor Domingos Cardoso for the rst time in July 2004 in Paris at the Conference on Graph Theory devoted to Claude Berge. Domingos explained me his idea to organize in Aveiro a conference on Graph Spectra. I supported this idea since such a conference, devoted solely to Graph Spectra, had not been held before. Other colleagues also liked this idea and the Scienti c Committee for such conference was formed in December 2004. The corresponding web page was created in April 2005. Professor Cardoso invited me to visit Aveiro and I came to Aveiro in May 2005. After many preparations through correspondence, the rst Conference on Graph Spectra was held on 10 - 12 April 2006 in Aveiro. Domingos and I met several times also in Belgrade. In particular, he was kind to take part in conferences Spectra of Graphs and Applications 2006 and 2016. Also, we have published a few joint papers. For the future, I wish Professor Cardoso all the best in his life and in his scienti c work. Professor Dragoť Cvetković Mathematical Institute, Serbian Academy of Sciences and Arts, Belgrade, Serbia