title: Pd(2)@Sn(18)(4-): fusion of two endohedral stannaspherenes.
authors.affiliation: Department of Physics, Washington State University, 2710 University Drive, Richland, Washington 99354, USA.
authors.forename: Zhong-Ming
authors.initials: ZM
authors.lastname: Sun
authors.forename: Hai
authors.initials: H
authors.lastname: Xiao
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Lai-Sheng
authors.initials: LS
authors.lastname: Wang