Blues from the 50s/60s/70s

You are right Jorsan. I misjudged, and I apologize. And your english is fine.

I strongly urge you to divide your search into 2 aspects: pre-war (before 1944) and post-war (after 1944).

I think that electric 'urban' blues became a caricature of itself after the early '60s. So for post-war I recommend 1944-1965. Maybe begin within these time frames.

Check out all the artists on Chess records. For pre-war check out the Yazoo catalouge, for starters. Here is a partial list of my favorites from both periods: Sonnyboy Williamson, Howlin Wolf, Otis Rush, Elmore James, Robert Wilkins, Son House, Blind Willie Johnson, Tommy Johnson, Charley Patton, Sam Collins, John Hurt, Skip James...to name but a few.

I know that the sound is more 'crude' in an audiophile sense, but I think that material from after the mid-sixties is much inferior in an artistic sense, with a few exceptions. Also it would be a shame to overlook the jewels of the pre-war period, which I strongly suggest. It might be quite challenging to an audiophile to digest something like Charley Patton, for example, due to the sound quality. However you will be greatly rewarded. No question about it. In fact, if you buy and do not like Charley Patton on purely musical grounds, I will refund your purchase (maybe). Just kidding, but try it.

Chashmal, thanks for your post and your comments. I think your offers us a valuable information and you can be sure that will follow your advice. I never thought that I could find this amount of great and valuable information just for posting a simple question. Now Im more interested than ever in the "blues" world.
To be more involved in this field, what about a recomendation of a good reading? will be fabulous to have one or two books about the history and evolution of the blues in the US, and maybe another one or two titles about the explosion of the blues in the UK in the 60's.
Thanks again to all, Im learning every day.

For historical background, check out the work of Samuel Charters. Here is a partial bibliography.
1959 - The Country Blues. New York: Rinehart. Reprinted by Da Capo Press, with a new introduction by the author, in 1975.
1963 - The Poetry of the Blues. With photos by Ann Charters. New York: Oak Publications.
1963 - Jazz New Orleans (1885-1963): An Index to the Negro Musicians of New Orleans. New York: Oak Publications
1967 - The Bluesmen. New York: Oak Publications
1975 - The Legacy of the Blues: A Glimpse Into the Art and the Lives of Twelve Great Bluesmen: An Informal Study. London: Calder & Boyars.
1977 - Sweet As the Showers of Rain. New York: Oak Publications
1981 - The Roots of the Blues: An African Search. Boston: M. Boyars.
1984 - Jelly Roll Morton's Last Night at the Jungle Inn: An Imaginary Memoir. New York: M. Boyars.
1986 - Louisiana Black: A Novel. New York: M. Boyars.
1991 - The Blues Makers. (Incorporates The Bluesmen and Sweet As the Showers of Rain) Da Capo.
1999 - The Day is So Long and the Wages So Small: Music on a Summer Island. New York: Marion Boyars.
2004 - Walking a Blues Road: A Selection of Blues Writing, 1956-2004. New York: Marion Boyars.
2006 - New Orleans: Playing a Jazz Chorus. Marion Boyars.

Wow!! I will need 5 lifes to read all that !!!!