Regarding the individual chapters in the Studies in Abundant Living, I,II,III series, these were originally small, individual paperbound commentaries that were handed out to class students until they (the commentaries) were later assembled into hardbound books. When I took the class in 1972, they were, at that point, hardbound but the individual chapters could be purchased through the bookstore. I still have most, if not all, of mine. There were also some that never made it into book form. These included some by Earl Burton, Peter Wade, Dorothy Owens and probably some I don't remember.