Where was the tournament that happened in 1987 on a clay surface?
CREATE TABLE "doubles_titles_28" (
  "date" real,
  "tournament" text,
  "surface" text,
  "partnering" text,
  "opponent_in_the_final" text,
  "score" text
);
SELECT "tournament" FROM "doubles_titles_28" WHERE "date"=1987 AND "surface"='clay';