1999DIN EN ISO 4157-3:1999-03 Construction drawings - Designation systems - Part 3: Room identifiers (ISO 4157-3:1998); German version EN ISO 4157-3:1998
1999DIN EN ISO 4157-3:1999 Construction drawings - Designation systems - Part 3: Room identifiers (ISO 4157-3:1998); German version EN ISO 4157-3:1998