Multi-photon production in e+e- collisions at √s=181-209 GeV - Abbiendi,G; Ainsley,C; Åkesson,PF; Alexander,G; Allison,J; Amaral,P; Anagnostou,G; Anderson,KJ; Arcelli,S; Asai,S; Axen,D; Azuelos,G; et al. (EUROPEAN PHYSICAL JOURNAL C, 2003)