Marugame T, Sobue T, Nakayama T, Suzuki T, Kuniyoshi H, Sunagawa K, Genka K, Nishizawa N, Natsukawa S, Kuwahara O, Tsubura E. Filter cigarette smoking and lung cancer risk; a hospital-based case–control study in Japan. British Journal of Cancer. 2004 Feb 03;90(3):646–51. doi: 10.1038/sj.bjc.6601565.