CREATE TABLE table_76996 ("Date" TEXT, "Opponents" TEXT, "H / A" TEXT, "Result F \\u2013 A" TEXT, "Attendance" FLOAT)

When did Manchester United play against Bristol City with an H/A of A?
SELECT "Date" FROM table_76996 WHERE "H / A" = 'a' AND "Opponents" = 'bristol city'
SELECT "Date" FROM "table_76996" WHERE "H / A" = 'a' AND "Opponents" = 'bristol city'