Entries made in the records or other documents of a railway administration shall be admitted in evidence in all proceedings by or against the railway administration, and all such entries may be proved either by the production of the records or other documents of the railway administration containing such entries or by the production of a copy of the entries certified by the officer having custody of the records or other documents under his signature and stating that it is a true copy of the original entries and that such original entries are contained in the records or other documents of the railway administration in his possession.