It shall be unlawful for any person, partnership, agency, firm or corporation, or officer or agent thereof, knowingly to recruit, solicit or advertise for employes or refer persons to employment in place of employes involved in a labor dispute without adequate notice to such person or in such advertisement that there is a labor dispute at the place at which employment is offered and that the employment offered is in place of employes involved in such labor dispute.
43 P.S. § 217.25