A map of 2008 North Sumatra gubernatorial election in each regencies and cities.  Ali Umri and Maratua Simanjuntak  Tritamtomo and Sahala Benny Pasaribu  Robert Edison Siahaan and Suherdi  Abdul Wahab Dalimunthe and Raden Muhammad Syafii  Syamsul Arifin and Gatot Pujo Nugroho
Dinamika Politik Sumatera Utara 2010, p. 172
Vectorization:  Jeromi Mikhael