Every ordinance or resolution adopted by the council shall be signed by the mayor or by two other members, attested by the City Administrator and filed and preserved by him. Every ordinance shall be published once in the official newspaper or posted in three conspicuous places within the City. To the extent and in the manner provided by law an ordinance may incorporate by reference a statute of Minnesota, a state administrative rule or a regulation, a code, or ordinance or part thereof without publishing or posting the material referred to in full.