Generally, English requires you to be more specific in this arena. Typically, an EN text would say prints, drawings, watercolours or whatever. We don't speak about sheets, pages, or so on, in a museum collection. Although longer 'works on paper' is the generic term, including all of the above, and printed ephemera may also be included in some collections, though in others they would represent a different category.

The Art collection at the National Museum Cardiff houses 28,000 works on paper. These comprise watercolours, drawings, prints, sketchbooks and albums. It is a broad-based collection, ranging from prints by Rembrandt and Picasso to watercolours by Cézanne and Turner and drawings by Burne-Jones and David Nash. There are particularly extensive holdings of works by Augustus and Gwen John (over 2,000 works), Graham Sutherland, David Jones and Ray Howard-Jones. These give a unique insight into the working methods of these artists. We also have a large collection of topographical views of Wales.
http://www.museumwales.ac.uk/en/108/

An auction may describe works on paper in terms of 'sheet size' but I've never heard anyone refer to sheets in general.

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Note added at 45 mins (2013-07-20 10:13:01 GMT)
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Easily done; it's the same in German and I know my mind can get too close to the source terminology when I'm tired! I guess it is the nature of our work.