Government Information: Maps: Map Information

"This tool permits the user to convert latitude and longitude between decimal degrees and degrees, minutes, and seconds. For convenience, a link is included to the National Geodetic Survey's NADCON program, which allows conversions between the NAD83 / WGS84 coordinate system and the older NAD27 coordinate system. NAD27 coordinates are presently used for broadcast authorizations and applications."

Oregon Department of Environmental Quality

Department of the Army

Reading topographic maps: Activities for earth science teachers and students. Oklahoma Geological Survey. James R. Chaplin

Page 37 has helpful information on latitude & longitude.