When I speak of early editions to be clear I am making a statement as to the quality of bookmaking (better quality) as opposed to much later releases of this great encyclopedic set of books.
The first 6 volumes are all pre-1954 and number 7 came in 1972 written and edited by Harry Lorayne having a three way index of accessing information within all 7 volumes. Tarbell number 8 released in 1993 although written and illustrated by Harlan Tarbell was edited by Steve Burton and Richard Kaufman.
The value to be received from this great set far exceeds the amount of money you may invest. Condition of books range from good to like new.