I always go back to the Public and Broadcasting Manual
Station-Conducted Contests. A station that broadcasts or advertises information about a contest that it conducts must fully and accurately disclose the material terms of the contest and must conduct the contest substantially as announced or advertised over-the-air or on the Internet. Contest descriptions may not be false, misleading, or deceptive with respect to any material term. Material terms, include those factors that define the operation of the contest and affect participation, such as entry deadlines, the prizes that can be won, and how winners will be selected. The station conducting the contest must disclose material terms either through periodic disclosures broadcast on the station, or written disclosures on the station’s Internet website, the licensee’s website, or if neither the individual station nor the licensee has its own website, any Internet website that is publicly accessible. Additional information about the contest rule can be found at https://www.fcc.gov/consumers/guides/broadcasting-contests-lotteries-and….
At this link you can find the attached PDF Consumer Guide.
The latest Rules can be found by doing a Google Search “FCC Title 47 CFR”
This will give you a link to all the FCC Rules. Part 0-199. The rules covering broadcast stations are found in Part 73.
The latest contest rules can be found in Title 47 CFR Section 73.1216 using this link