Here are 2 original Nostromo bridge dyeline prints used during production of A L I E N.

The first one was drawn (and signed on the right) by no other than Ron Cobb and shows the bridge of the spaceship as seen from the rear. The angle of vision allows to see various computer screens, panels full of switches, chairs and tons of surface details that were later (for the most part) reproduced at scale 1:1 on the set.

The second one came from the Art Department.
It was drawn in April 1978 by someone named "Crispian" and under direct supervision of Michael Seymour, production designer of A L I E N, who signed it. It's a stage layout that shows the set of the Nostromo Level A bridge as seen from above, with cockpit, galley, dining room, MU-TH-UR room, infirmary and various corridors connecting the rooms together.
The layout bears number 506 and refers to Stage C (at Shepperton) where this set was later built.

Both dyeline prints are in fine condition even if pretty fragile because they were printed on thick paper.

They were acquired from 2 different sources.

Note : A dyeline is a way of copying drawings, much like a photocopy. The process focuses on the lines rather than the tone, giving an instantly recognizable aspect to the prints.