What keywords would bring up images of those symbols or maps with those symbols?
I used “sample location symbols” and got this from a GIS software. All variations on a circle with a cross.
http://www.google.com/imgres?imgurl=http://www.geoanalysis.com/images/Visual%2520Site%2520Manager%2520description_files/vsm_loceditor_big.jpg&imgrefurl=http://www.geoanalysis.com/environmental_database_software_vsm_detail.htm&usg=__zoPtTLl0FvetqOe778UZrZhPyD8=&h=369&w=571&sz=64&hl=en&start=19&zoom=1&tbnid=sWTwOcOaEY2SSM:&tbnh=111&tbnw=172&prev=/images%3Fq%3Dsample%2Blocation%2Bsymbols%26um%3D1%26hl%3Den%26biw%3D1419%26bih%3D724%26tbs%3Disch:10%2C724&um=1&itbs=1&ei=SO8pTYLWKcL78AaN16j6AQ&biw=1419&bih=724&iact=rc&dur=271&oei=KO8pTcGuHoH78AbbzJTFDQ&esq=2&page=2&ndsp=30&ved=1t:429,r:25,s:19&tx=105&ty=64
