Whenever any party considers any document in the administrative file essential to any further proceedings under the Act, it is the responsibility of such party to obtain such document from the district director and reintroduce it for the record before the administrative law judge. The type of document that may be obtained will be limited to documents previously submitted to the district director, including documents or forms with respect to notices, claims, controversions, contests, progress reports, medical services or supplies, etc. The work products of the district director or his staff will not be subject to retrieval. The procedure for obtaining documents will be for the requesting party to inform the district director in writing of the documents he wishes to obtain, specifying them with particularity. Upon receipt, the district director must promptly forward a copy of the requested materials to the requesting party. A copy of the letter of request and a statement of whether it has been satisfied must be kept in the case file.