RT Journal Article SR Electronic T1 Reference value of six-minute walking distance in healthy middle-aged and older subjects JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 1132 OP 1133 VO 15 IS 6 A1 Teramoto, S A1 Ohga, E A1 Ishii, T A1 Yamaguchi, Y A1 Yamamoto, H A1 Mastsuse, T YR 2000 UL http://erj.ersjournals.com/content/15/6/1132.abstract AB