Book  (Apr 1999)  Page(s) 134-135.  
 
[Rivers'] Single Crimson Moss the number of its petals seems to increase annually... from being quite single [to] semi-double...

Rivers' Single Crimson Moss ('Single Crimson') Moss. Rivers, pre-1838. The author cites information from different sources... brilliant crimson, changing to purplish crimson... The number of its petals seems to increase annually, as in the '[Rivers'] Single Crimson Moss', which, from being quite single, is now semi-double...

Book  (1936)  Page(s) 179.  
 
Cramoisi à fleurs simples (moss) Rivers 1856; crimson, medium size, single.

Book  (1899)  Page(s) 44.  
 
Cramoisi à fleurs simples, centifolia muscosa, Rivers, 1856, cramoisi

Book  (1848)  Page(s) 39.  
 
Summer Roses, blooming in May, June, and July.
Rosa centifolia.
The Moss Rose.
74. Single Crimson; flowers brilliant crimson, changing to purplish crimson, large and single, sometimes semi-double; form, expanded. growth, vigorous; foliage of a fine dark green.

Book  (1837)  Page(s) 10.  
 
Rivers's Single Moss is inclined to be semi-double. This is a remarkably luxuriant grower, as is the Single Crimson Moss, a seedling which bloomed for the first time in the season of 1836; a rose quite worth notice, for its colour is beautiful; and, as it is a true Moss Rose, and bears seed abundantly, it will, I hope, be the parent of some first-rate varieties.