New symmetric and planar designs of reversible full-adders/subtractors in quantum-dot cellular automata Moein Sarvaghad-Moghaddam and Ali A. Orouji Eur. Phys. J. D, 73 6 (2019) 125 Published online: 18 June 2019 DOI: 10.1140/epjd/e2019-90315-x