PUBLIC LAWS-CH. 146-MAY 27, 1949 Examination of rec- ords, etc., by Assessor. Penalty. (d) to require any vendor selling to persons within the District to keep detailed records of the nature and value of personal property sold for use within the District, and to furnish such information upon request to the Assessor; (e) to assess, determine, revise, and readjust the taxes imposed under this title. SEC. 145. The Assessor, for the purpose of ascertaining the correct- ness of any return filed as required by this title, or for the purpose of making a return where none has been made, is authorized to examine any books, papers, records, or memoranda, or any person bearing upon the matters required to be included in the return and may summon any person to appear before him and produce books, records, papers, or memoranda bearing upon the matters required to be included in the return and to give testimony or answer interrogatories under oath respecting the same, and the Assessor, or his duly authorized repre- sentative, shall have power to administer oaths to such person or persons. Such summons may be served by any member of the Metro- politan Police Department. If any person, having been personally summoned, shall neglect or refuse to obey the summons issued as herein provided, then in that event the Assessor, or the Deputy Assessor, may report that fact to the United States District Court for the District of Columbia, or one of the justices thereof, and said court or any justice thereof hereby is empowered to compel obedience to said sum- mons to the same extent as witnesses may be compelled to obey the subpenas of that court. Any person in custody or control of any books, papers, records, or memoranda bearing upon the matters required to be included in such returns, who shall refuse to permit the examination by the Assessor or any person designated by him of any such books, papers, records, or memoranda, or who shall obstruct or hinder the Assessor or any person designated by him in the examination of any books, papers, records, or memoranda, shall upon conviction thereof be fined not more than $500 or imprisoned for not more than six months, or both, for each offense. REGISTRATION SEC. 146. (a) No person shall engage or continue to engage in the business of making any retail sales subject to tax under the provisions of this title without having obtained a certificate of registration therefor. If two or more persons constitute a single vendor as defined in this title, such persons may operate a single retail establishment under one certificate of registration and in such case neither the death or retirement of one or more of such persons from business in such establishment nor the entrance of one or more persons thereinto shall affect the certificate of registration for a period of sixty days or require the issuance of a new certificate until the expiration of such period. (b) Each applicant for a certificate required by this section shall make out and deliver to the Assessor, upon a blank to be furnished by him for that purpose, a statement showing the name of the appli- cant, each retail establishment where the applicant's business is to be conducted, the kind or nature of such business and such other information as the Assessor may prescribe. Upon receipt of such application the Assessor shall issue the applicant, without charge, a certificate of registration for each retail establishment designated in the application, authorizing the applicant to engage in business at such retail establishment. The certificate of registration shall be nontransferable except as otherwise provided in thiis title, and shall be displayed in the applicant's place of business. The form of such certificate of registration shall be prescribed by the Assessor. 122 [63 STAT.