CREATE TABLE table_name_20 (catalog VARCHAR, format VARCHAR, date VARCHAR)

Released on April 12, 1968 in LP format, what was the catalog?
SELECT catalog FROM table_name_20 WHERE format = "lp" AND date = "april 12, 1968"
SELECT "catalog" FROM "table_name_20" WHERE "april 12, 1968" = "date" AND "format" = "lp"