The ornamental design for a refrigerator, as shown and described.
FIG. 1 is a perspective view of a refrigerator, showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left-side view thereof;
FIG. 5 is a right-side view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof;
FIG. 8 is an enlarged perspective view of the claimed portion of the refrigerator;
FIG. 9 is an enlarged front view thereof;
FIG. 10 is an enlarged rear-side view thereof; and,
FIG. 11 is an enlarged left-view thereof.
The broken lines in the drawings show unclaimed environmental detail only and form no part of the claimed design.
The shade lines in the figures show contour and not surface ornamentation.
The dot-dot-dash lines immediately adjacent the claimed line in the figures represent an unclaimed boundary line and form no part of the claimed design.