Retrieved 11 May 2017. a native or resident of Springfield (such as Springfield in Illinois, Massachusetts, or Ohio) : springfielder "Total Real Gross Domestic Product for Springfield, MA (MSA)".
Diakses tanggal 11 May 2017. a native or resident of Springfield (such as Springfield in Illinois, Massachusetts, or Ohio) : springfielder Pemeliharaan CS1: Bahasa yang tidak diketahui (link) ^ "Total Real Gross Domestic Product for Springfield, MA (MSA)".