A spiral nebula as a stellar system Messier 33

[1] *HARV, 271 HARV

[2] *HARV, 260 HARV

[3] *HARV, 1925, 280 HARV

[4] LUNDMARK, 1925, MONTHLY NOTICES, V85, P885

[5] PEASE, 1916, PUBLICATIONS ASTRONO, V28, P33

[6] SEARES, MT WILSON CONTR, V81

[7] SHAPLEY, HARVARD COLL OBSERVA, V816

[8] 1926, ASTROPHYSICAL J, V62, P409

[9] 1925, MONTHLY NOTICES, V85, P890

[10] MT WILSON CONTR, V262

[1] *HARV, 271 HARV

[2] *HARV, 260 HARV

[3] *HARV, 1925, 280 HARV

[4] LUNDMARK, 1925, MONTHLY NOTICES, V85, P885

[5] PEASE, 1916, PUBLICATIONS ASTRONO, V28, P33

[6] SEARES, MT WILSON CONTR, V81

[7] SHAPLEY, HARVARD COLL OBSERVA, V816

[8] 1926, ASTROPHYSICAL J, V62, P409

[9] 1925, MONTHLY NOTICES, V85, P890

[10] MT WILSON CONTR, V262