D → π and D → K semileptonic form factors with Nf = 2 + 1 + 1 twisted mass fermions Vittorio Lubicz, Lorenzo Riggio, Giorgio Salerno, Silvano Simula and Cecilia Tarantino EPJ Web Conf., 175 (2018) 13026 Published online: 26 March 2018 DOI: 10.1051/epjconf/201817513026