Pauline Barmby's "Notes for discussion of Heiles' 1979 paper," presented
in Astronomy 208, October 10, 1996:

-survey has pretty lousy resolution (36')
-seems strange that they are transforming digital
 data to nonlinear pictures (optical astronomers)
 were starting to do the exact opposite about the same time)
-a lot of selection effects in this survey

-expanding shell: changes size with velocity
-what's going on with the negative and positive velocity shell stuff (p. 
536)?
-estimating distances is tricky.
-difficulty getting energies
-difficulty correlating these things with other objects
conclusion: they see these things but can't measure them very well
and don't know what they are. Better resolution would help to tell if
they are real.

context:
as of 1984 (APJS paper) - still no unique explanation
1989 paper: magnetic pressure important in shells (67x thermal pressure)
- type III supernovae: a Zwicky idea no one else bought into
- 1996: paper by Rand et al.: 
        modelling supershell in N4631 as results of impact of
        high velocity cloud with galactic disk
- 1995: paper by Maciejewski et al: one of Heiles' supershells
        as multiple SNR