68 Pa. Stat. § 374
In all cases, in the city of Philadelphia, where there is a lease, or verbal letting, of property, for a term of years, or from year to year, and the landlord, whether the owner, at the time of such lease or letting, or by purchase subsequent thereto, has lost the lease, or evidence of the beginning and conclusion of the term, or cannot produce proof of the same, it shall be lawful, at any time after the first year, or after the term of years, as the case may be, for the landlord desiring to recover possession of the demised property, to give notice, in writing, to the tenant, that he has lost such lease, or is unable to make such proof, and requiring the tenant, within thirty days from the time of service of such notice to furnish him, in writing, with the date at which his term of tenancy commenced, and such notice, if supported by affidavit, shall be evidence of what it sets forth; if the tenant shall furnish, in writing, the date, as required, such writing shall be evidence of the facts contained in it; but if the tenant shall fail, or refuse, within thirty days, to comply with the said requirement, the landlord may, at the expiration of that period, give to the tenant three months' notice to quit the premises occupied by him, and shall proceed, thereafter, in the same manner as is now provided in cases of the usual notice to quit at the end of the term: Provided, That if the tenant shall make affidavit, within the thirty days aforesaid, that he is unable to comply with the requirements of the landlord, stating the causes of such inability, the landlord shall give six months' notice to the tenant to remove from the demised premises, upon which he shall proceed, as provided in the cases of the three months' notice, as aforesaid.
68 P.S. § 374