CREATE TABLE table_52308 ("Call sign" TEXT, "Frequency MHz" FLOAT, "City of license" TEXT, "ERP W" FLOAT, "Class" TEXT, "FCC info" TEXT)

What is the call sign for a class of A?
SELECT "Call sign" FROM table_52308 WHERE "Class" = 'a'
SELECT "Call sign" FROM "table_52308" WHERE "Class" = 'a'