Article (magazine)  (Dec 2015)  Page(s) 20-21.  
 
Around 1870 the Director of the Botanic Gardens of the St Petersburg Scientific Academy, Eduard Regel, released a purplish-red flowered rose as ’Tsaritsa Severa’, ’Kaiserin des Nordens’ (R. davurica x a rugosa). The nursery of Regel & Kesselring in St Petersburg sent plants to Finland, where the rose became known as ’Pohjolan Kuningatar’, i.e., ”Queen of the North”. This rose has persisted in Finnish gardens further north as well. ’Kaiserin des Nordens’ forms an elegant bush with rather small, fresh green, narrowly pointed leaflets. The smallish flowers are double, dark purplish-red. There is little or no reblooming and no hips are formed.

Article (website)  (2005)  Page(s) 8.  
 
"Professor Eduard Regel,... introduced three Rugosas: 'Regeliana' (1871), 'Regeliana Alba' (ca. 1871), and in 1879 'Regeliana Flore Plena' aka 'Kaiserin des Nordens'.

Article (website)  (2005)  Page(s) 5.  Includes photo(s).
 
Pohjolan Kuningatar or 'Tsaritsa Severa' or 'Kaiserin des Nordens' (rugosa-group)

Book  (19 Apr 2000)  Page(s) 487.  
 
R. rugosa plena species, mauve. Synonyms: Rosa pubescens, R. rugosa rebro-plena

Book  (1976)  Page(s) 60.  
 
Under the harsh climatic conditions of St. Petersburg, Regel busied himself with breeding roses; he selected a form of R. rugosa, the so-called 'Zariza Swera' (1879).

Magazine  (Feb 1953)  Page(s) 1. trimester, p. 4.  
 
Rugosa rubra (Taicoun), grande fleur simple ou semi-double rouge violacé très odorante.

Magazine  (Apr 1938)  Page(s) 11.  
 
Rosa rubra plena Hort. H. Rug. Hauteur : 2 m . , fleurs rouges, pleines, en mai-juin.

Book  (1937)  Page(s) 72.  
 
Kaiserin des Nordens Rugosa (variety of kamtschatica Vent.)

Book  (1936)  Page(s) 516.  
 
Nordens, Kaiserin des (rugosa) Regel 1879; violet-purple, 7cm., well double, flat, in clusters of 3-7, fragrance 4/10, once-blooming, occasional repeat, growth 8/10, upright, 1.50m., hardy. = R: Regeliana. Sangerhausen

Book  (1936)  Page(s) 633.  
 
Rubra à fleur pleines (rugosa) Regel ? ; violet-red, double.
Rubra plena (rugosa) Regel ? ; dark cherry-red to violet-purple, large, double, growth 7/10, upright, bushy. = Himalayensis; Kaiserin des Nordens. Sangerhausen