b) reproduction by means of photocopy or any other technical means, to wit visual or audio; c) issuance of certified copies by the public body [where the document is kept]. 2. Reproduction pursuant to paragraph 1b) shall be one copy and subject to payment by the applicant of an amount strictly corresponding to the cost of the materials used and the service rendered; such amount to be determined by a decree-law. 3. Documents in digital format shall be transmitted in a way that is intelligible to any person and such so that it constitutes an accurate match of the contents of the file, without detriment to the option provided for in paragraph 1b) of this article. 4. Where there is a risk that reproduction as provided for in paragraph 1b) may cause damage to the documents, the interested person, at his or her expense and under the supervision of the institution, shall be entitled to devise a manual reproduction or reproduction by any other means that does not harm the preservation of the document. Article 13 (Manner of request) Requests for access to documents must be made in writing and contain all references necessary for identifying the document, as well as the name, the address and the signature of the interested person. Article 14 (Responsibility for providing access) In each public authority, institution and statutory society there is an entity responsible for the implementation of the provisions of this law. Article 15 (Reply from public authorities) 1. The entity to whom a request for access to a document is made, must within a period of 10 days: a) communicate the date, place and manner in which to consult the document, reproduce it, or obtain a certified copy thereof; b) in terms of the provisions of Article 67 of the procedures for public authorities approved by Decree-Law 16-A/95, of 15 December, give reasons for the complete or partial refusal to grant access to the requested document; c) notify that the document is not within its possession and, if it knows of its whereabouts, point out the entity that possesses the document, or pass the request on to the latter and so inform the interested party;