On multi-term fractional differential equations with multi-point boundary conditions Bashir Ahmad, Najla Alghamdi, Ahmed Alsaedi and Sotiris K. Ntouyas EPJ - Special Topics, 226 16-18 (2017) 3369-3390 Published online: 25 July 2018 DOI: 10.1140/epjst/e2018-00009-3