The ornamental design for a two-dimensional sheet for a notebook, as shown and described.
FIG. 1 is a perspective view of the two-dimensional sheet for a notebook showing my new design;
FIG. 2 is a front view thereof; and,
FIG. 3 is a partial enlarged view of a portion of the two-dimensional sheet for a notebook defined by the dash-dot-dash line labeled 3 in FIG. 2.
The broken lines and dot chain lines depict environmental subject matter only, and form no part of the claimed design. The claimed design is a sheet having only two dimensions; thus, the top view, right-side view, left-side view, and bottom view are not depicted.