CREATE TABLE table_51181 ("Romaji title" TEXT, "Japanese title" TEXT, "Release date" TEXT, "Reference" TEXT, "Oricon" FLOAT)

What is the reference for the romani title da.i.su.ki?
SELECT "Reference" FROM table_51181 WHERE "Romaji title" = 'da.i.su.ki'
SELECT "Reference" FROM "table_51181" WHERE "Romaji title" = 'da.i.su.ki'