Chiba-ken (Japan). Shizen Hogoka

• Chiba-ken Gyōtoku Yachō Kansatsusha
• Chiba-ken shizen kankyō hozen chiiki tō hensen chōsa hōkokusho
• Chiba-ken shizen kankyō hozen gakujutsu chōsa hōkokusho
• Heisei 18-nendo gairaishu kinkyū tokubetsu taisaku jigyō (kyon no seisoku jōkyō tō chōsa) hōkokusho