"Programming semantics for multiprogrammed computations" (at citeseer.ist.psu.edu ) is the original capability paper.
This paper can also be found at www.lcs.mit.edu
Cite Seer seems to be giving a blank page for this, but citeseer.ist.psu.edu is similar.
For the first link try citeseerx.ist.psu.edu
See original on c2.com