CREATE TABLE table_204_843 (id NUMBER, "volume" NUMBER, "year" CLOB, "names" CLOB, "articles" NUMBER, "pages" NUMBER, "images" NUMBER, "maps" NUMBER, "number of copies" NUMBER)

how many fewer maps were present between the 1986 and 1983 editions ?
SELECT ABS((SELECT "maps" FROM table_204_843 WHERE "year" = 1986) - (SELECT "maps" FROM table_204_843 WHERE "year" = 1983))
SELECT ABS((SELECT "maps" FROM "table_204_843" WHERE "year" = 1986) - (SELECT "maps" FROM "table_204_843" WHERE "year" = 1983))