A spiral nebula as a stellar system Messier 33

[21] MT WILSON CONT, V47

[22] 1925, P AM ASTR SOC 33 M J

[23] 1922, ASTROPHYSICAL J, V46, P400

[24] 1923, ASTROPHYSICAL J, V57, P294

[25] 1922, ASTROPHYSICAL J, V56, P400

[26] 1922, ASTROPHYSICAL J, V55, P242

[27] 1910, ASTROPHYSICAL J, V32, P26

[28] 1920, P NATL ACAD SCI, V6, P293

[29] 1899, PHOTOGRAPHS STARS ST, V2, P66

[30] 1924, PUBLICATIONS DOMINIO, V2

[21] MT WILSON CONT, V47

[22] 1925, P AM ASTR SOC 33 M J

[23] 1922, ASTROPHYSICAL J, V46, P400

[24] 1923, ASTROPHYSICAL J, V57, P294

[25] 1922, ASTROPHYSICAL J, V56, P400

[26] 1922, ASTROPHYSICAL J, V55, P242

[27] 1910, ASTROPHYSICAL J, V32, P26

[28] 1920, P NATL ACAD SCI, V6, P293

[29] 1899, PHOTOGRAPHS STARS ST, V2, P66

[30] 1924, PUBLICATIONS DOMINIO, V2