The ornamental design for a sheet of paper with a watermark, as shown and described.
FIG. 1 is a top plan view of a sheet of paper with a watermark showing our
new design, the bottom plan view being substantially identical thereto.
The side views of the sheet of paper with a watermark are plain and
unornamented. The broken lines in FIG. 1 are shown to indicate the
peripheral boundries of the paper and form no part of the claimed design.
The characteristic feature of the watermark design for the sheet of paper
resides on the top and bottom surfaces of the sheet of paper, as shown.