A broker shall not advertise the sale, purchase, exchange, rent or lease of real estate, for another or others, in a manner indicating the offer to sell, purchase, exchange or lease 'is being made by a principal. Every such advertisement shall clearly indicate that it is the advertisement of a broker or brokerage firm and shall not be confined to publication of only a post office box number, telephone number, or street address.

A salesman shall not advertise the sale, purchase, exchange, rent or lease of real estate, for another or others, without his broker's consent and without including in the advertisement the name of the broker or firm with whom he is associated.

A broker shall not display a "For Sale" or "For Rent" sign on any real estate without the consent of the owner or his authorized agent.