I have seen some Atlases and Maps where North or South or plus(+) for North or minus(-) for south is not mentioned/suffixed with the degrees of Latitudes in the graticules. Is it correct? How will a user find out whether she is looking at the map of an area in Northern Hemisphere or Southern Hemisphere. Similarly East and West are also not mentioned in many maps.
I think you would have to go by the directions that the latitude or longitude values are increasing. As long as the coordinate reference system being used is a easting, northing one, latitude values will increase upwards, in the map/page sense, in the northern hemisphere and downwards in the southern hemisphere. Similarly, longitude values will increase to the right in the easting hemisphere, and to the left in the western hemisphere.