is there any unusual type of edition present of this third one?
Yes. A "fig-leaf edition" with the offending nine pages blacked out
Oil!
 Sinclair's publisher printed 150 copies of a "fig-leaf edition" with the offending nine pages blacked out. 
what is referred as weird tales? American fantasy and horror fiction pulp magazine from where did this kind of magazine originate? UNANSWERABLE what are the genres of this last kind of magazine you mentioned? American Old West did it reach any height of popularity? Yes. At their peak of popularity in the 1920s-1940s, the most successful pulps could sell up to one million copies per issue can you name any of its author? Upton Sinclair and who is the writer of the above magazine? H. P. Lovecraft, Seabury Quinn and Clark Ashton Smith when was it published? First issue appeared on newsstands on February 18, 1923 which other editions does it have? A Canadian edition does the very first rather former author involved in politics by any chance? Yes. He was the Socialist party candidate for governor of California in 1926 what else has he written other than in the magazine? Novels such as "King Coal", "The Coal War", "Oil!" and "The Flivver King"
wiki:12593609
Oil! [SEP] Fig-leaf edition
"Oil!" was banned in Boston for its motel sex scene. Sinclair's publisher printed 150 copies of a "fig-leaf edition" with the offending nine pages blacked out. Sinclair protested the banning and hoped to bring an obscenity case to trial. He did not do so, but the controversy helped make the book a bestseller.