Use the citation form of the numeral

Error²Federal courts, Illinois courts21st and 22nd editions

In citations second and third take the shorter forms “2d” and “3d” — “2d Cir.”, “3d Cir.”, “F.3d”, “Ill. App. 3d”, and the Illinois Appellate Court’s “(2d)” and “(3d)” districts.¹

1. 1R. 6.2(b)(ii) Ordinals; R. 6.2(b)(i) Ordinals.
2. 2An error: the rule in note 1 allows one form, and this is not it.