@article{RSMUP_1979__61__115_0,
     author = {Invernizzi, S. and Zanolin, F.},
     title = {Periodic solutions of a differential delay equation of {Rayleigh} type},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
     pages = {115--124},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {61},
     year = {1979},
     mrnumber = {569654},
     zbl = {0429.34064},
     language = {en},
     url = {http://archive.numdam.org/item/RSMUP_1979__61__115_0/}
}