Find String Between Characters

Dear R Helpers,

I am trying to isolate a set of characters between two other characters in
a long string file.  I tried some of the examples on the R help pages and
elsewhere, but I am not able to get it.  Your help would be much
appreciated.

require(scrapeR)
mmm<-scrape(url="http://www.sec.gov/cgi-bin/browse-edgar?action=getcompany&CIK=0000320193&owner=exclude&count=40")
str(mmm)

I want to get the number 0000320193 that is between the CIK= and the &.  I
have tried

g <- grep( "CIK=|&", mmm )
and
temp<-grep(mmm,\CIK=\&)

and variations on these themes, but all won't run or come bask as an empty
object.  How can I grab this number?

Best wishes,
--John J. Sparks, Ph.D.