Spirit in the Sky
Which Way You Goin' Billy
Candida
Ain't no Mountain High Enough
I'll be There
Signed, Sealed, Delivered I'm Yours
Hitchin a Ride
Hey There Lonely Girl
I think I Love You
Ride, Captain Ride
Ooh Child
Green-eyed Lady
Love Grow Where my Rosemary Goes
In the Summertime
Lookin out my back door
Rainy Night in Georgia
Give me just a little more time
Snowbird
Cecelia
United We Stand
We've only just begun
Evil Ways
I just can't help believing
Leavin' on a Jet Plan

May I ask why you are asking?  Are you perhaps attempting to prepare a
compilation of all these recordings or perhaps you wish to perform
them?  There are rights clearinghouses that offer "one-stop shopping"
for such endeavors . . .

Yes, Want to perform them inside a dramatic piece (musical revue).  My
understanding is that because they will be performed within a dramatic
piece, ASCAP is not an issue, but the copyright is.  I have a few
other songs from 1970 but I "know" the copyright holder for them; 
however, if what you say is true--  that there are one-stop shops for
this sort of thing--  then I should probably include ALL of the songs
in the list to go to the one-stop shop, not just the ones for which I
could not find a copyright.  Thank you for your question.  I've
already learned something.  Jan in Peoria

I think ASCAP is the place to start.  Get your whole list together and
then check out http://www.ascap.com/licensing/licensingfaq.html.  You
may also want to call the toll-free number and ask some questions. 
You certainly could approach each individual copyright holder
separately, but ASCAP does that for you.  This assumes that all of the
songs you want to perform are within the ASCAP repertoire of licensed
compositions.  If not, they can tell you who to contact for rights,
whether it be another performing rights society like BMI, or the
individual copyright owner.