Book  (Oct 2001)  Page(s) 185.  Includes photo(s).
 
Clematis 'Evitwo'
Trade name: Arctic Queen
Raymond Evison (England) 1989
Introduced by Guernsey Clematis Nursery 1994
Parentage unknown
... fully double flowers on both old wood from the previous season and new growth in the current one... Creamy white flowers... a dozen or more pointed and overlapping tepals...