Book  (1915)  Page(s) 176.  
 
Clematis. — There is no more popular hardy climber than the Clematis.  One or two should be grown in the smallest garden.  They can be used to cover any structure from a few feet to 50 feet high.  A selection of different sorts will ensure a succession of flowers from April to October. [...] There are numerous named varieties; a dozen of the best to furnish flowers from May to October are as follows:
Alba magna, white...

Website/Catalog  (1912)  Page(s) 77.  
 
Summer and Autumn Clematis.
In bloom from July to October.
These flower upon the wood of the current year's growth, and should therefore be pruned to five or six eyes. 
Alba Magna, one of the finest of all the whites...  2s. 0d

Website/Catalog  (1907)  Page(s) 65.  
 
Clematis in pots to plant out in spring and summer.
General Collection.
6 alba magna (lanuginosa), white.

Book  (1906)  Page(s) 52.  
 
Principal garden varieties of Clematis:
Lanuginosa type. (July to October.)
Alba magna... Pure white, broad sepals.

Book  (1898)  Page(s) 61.  
 
Variétés Horticoles
1er Groupe.—PATENS
Section II. — Lanuginosa.
Alba Magna (Jackman).  Fleurs à larges sépales parfaitement imbriqués, atteignant 20 centimètres de largeur, du plus beau blanc pur; anthères brunes.

Magazine  (1877)  Page(s) 260, 267.  
 
p. 260: Alba magna. — Gard. Chron., 1875, I, 584, fig. 140.

p. 267: Clematis Alba magna (Jackman), 26 mai 1875, s. de lanuginosa; blanc.

Magazine  (15 Jan 1876)  Page(s) 73.  
 
The New Plants of 1875. ... Of the shrubby series we have Mr. Jackman's Clematis alba magna gained without doubt the finest of all white-blossomed varieties of this noble and popular climber, the sepals being so broad that any two meet together across the intervening one, and thus form a more solid-looking than we get in the case of any other variety. 

Magazine  (1876)  Page(s) 56.  
 
Revue des plantes nouvelles de 1875.
Traduit du Gardeners' Chronicle, 1876, I, p. 73
Parmi les arbustes, nous avons dans le Clematis alba magna, de M. Jackman, sans aucun doute, la plus belle de toutes les variétés à fleurs blanches de cette noble et populaire liane ; ses sépales sont si larges qu'ils se recouvrent mutuellement pour former la fleur la plus solide de ce genre.

Magazine  (29 May 1875)  Page(s) 684.  Includes photo(s).
 
MESSRS. JACKMAN'S CLEMATISES.
Messrs. Jackman & Son's popular exhibition at Regent's Park has now been brought to a close, and we may fittingly call attention at its termination to some of the charming novelties which it has been the means of introducing to our notice. [...]
One of the finest novelties, however, was alba magna, of which we give a woodcut representation (fig. 140).  This has the leaves either simple and cordate or ternate with ovate leaflets, and woolly; and six to eight-sepaled flowers, the sepals being exceptionally broad, fully 3 inches across, roundish ovate in outline, apiculate, necessarily very much overlapped; the flowers are quite 8 inches across, and of a pure white, without a dash of the purple tint which so often soils the purity of these white flowers; the anthers are purplish brown, and the buds woolly and erect.  It appears to us to be the finest of all the whites yet raised, and the most perfect flower, as regards shape, which has yet been obtained.