I did a google search for the book New Images, New Paths: A History of
Women in Engineering in the United States, 1850-1980 by Martha Moore
Trescott, copyrighted and published in 1996, as the Library of
Congress verifies.  It was published by T & L Enterprises in Dallas,
Texas.  The LC holds at least two copies and lists several other
libraries which
libraries which hold copies.  In addition, I know of 15-20 other
libraries in the U. S. and Europe which hold copies.  Some of these
libraris are on the LC World Cat system.  Does Google pick up such
holdings and citations in online library cataglogues, especially that
of the Library of Congress and the World Cat system?  If not, will
Google begin to pick these up, and when?
I wonder why does a google search not pick up these holdings and
citations?

WorldCat is a subscription (fee-based) database so it's not surprising
that a search engine wouldn't pick up its content--indeed, given that
it is a subscription database, I'd be shocked if a search engine did
pick up their holdings (as would, I strongly suspect, the folks at
OCLC).

OCLC WorldCat
http://www.oclc.org/worldcat/

Generally speaking the contents of OPACs (online public access
catalogs) are not indexed by search engines.

Regards,
luciaphile-ga

Information in individual databases is frequently not searchable by a
search engine.  Like the other commentor stated, it may be because the
database is fee based or it simply falls under the heading of what is
called the "Invisible Web".  For information on the "Invisible Web"
and why they are not searchable look at the results on the page. 
There are also many books and articles written on the subject:

://www.google.com/search?hl=en&ie=ISO-8859-1&q=invisible+web

Thank you to the people at Google who respoonded to my question. I
didn't know about the Invisible Web but will look that up and read
about it. Again, thanks.

Martha M. Trescott--I'm glad to know about it; it answers a lot of my
questions.

Hi marty20-ga,

I use WorldCat in my job and can attest to the fact that it is indeed
a subscription, fee-based product. Some library OPACs do have their
records indexed by search engines, but at this moment in time that is
not the case.

You actually haven't received an "answer" to your question yet. I
posted a comment as did bowler-ga. If you are satisfied with what I
told you in my comment, I'd be happy to post it as an answer.

Incidentally, you can tell who is an official researcher by the fact
that their names are hyperlinked.

Hope that helps.

Regards,
luciaphile-ga

I do appreciate the comments, even though it is said I haven't yet
received an answer. I would like to wait for the answer, if you think
there will be one to the question of whether and when google will
begin to pick up on-line public access catalogs, including the Library
of Congress catalogue. Re your last comment,I am unclear as to whether
any OPAC's now are picked up by google and other search engines.  If
they pay a fee, then they are, I suppose.  If that is the case, I can
post another question at some point as to which ones these are, I'm
sure.

Thanks. At this time, I will continue to wait for an answer to my
original question.

Martha