Analysis of information sources in references of the Wikipedia article "World Trade Center" in Danish language version.
{{cite news}}: Tjek |url= (hjælp){{cite news}}: Tjek |url= (hjælp)Modern skyscrapers such as the World Trade Center, New York, have steel and concrete hull-and-core structures. The central core–a reinforced concrete tower–contains lift shafts, staircases, and vertical ducts. From this core, the concrete and steel composite floors span on to a steel perimeter structure; a lightweight aluminium and glass curtain wall encloses the building. This type of construction is the most efficient so far designed against wind forces.
E-J Electric set four generators on the roof of Tower 5, which was nine stories, as opposed to the 110-story Towers 1 and 2. E-J then ran high-voltage feeder cable to Towers 1, 2, 4 and 5, installed three substations and distributed power to the tenants.
Six 1,200-kilowatt(kW) emergency power generators located in the sixth basement (B-6) level provided a secondary power supply.
{{cite book}}: CS1-vedligeholdelse: Flere navne: authors list (link){{cite news}}: Eksplicit brug af et al. i: |first2= (hjælp)E-J Electric set four generators on the roof of Tower 5, which was nine stories, as opposed to the 110-story Towers 1 and 2. E-J then ran high-voltage feeder cable to Towers 1, 2, 4 and 5, installed three substations and distributed power to the tenants.
{{cite news}}: Tjek |url= (hjælp){{cite news}}: Tjek |url= (hjælp){{cite news}}: Eksplicit brug af et al. i: |first2= (hjælp)