Physical Review Letters, 112-25, 2014 doi:10.1103/PhysRevLett.112.257401
Ulstrup Søren, Johannsen Jens Christian, Cilento Federico, Miwa Jill A., Crepaldi Alberto, Zacchigna Michele, Cacho Cephise, Chapman Richard, Springate Emma, Mammadov Samir, Fromm Felix, Raidel Christian, Seyller Thomas, Parmigiani Fulvio, Grioni Marco, King Phil D. C., Hofmann Philip