Make a yogurt incubator from two tin cans and an electric light socket and cord.
MOTHER EARTH NEWS #14 Mar 1972 pg. 73
Added Info MOTHER EARTH NEWS #16 Jul 1972 pg. 43
How to make your own yogurt.
MOTHER EARTH NEWS #62 Mar-Apr 1980 pg. 194
A guide to fermented milk forms (piima, kefir, acidophilus and yogurt) and how to make them.
ORGANIC GARDENING May 1979 (v.26#5) pg. 108