"Whole Lotta Love" was Led Zeppelin's only US Top 10 hit, charting at #4. Many of their songs, including "Stairway To Heaven," were not released as singles, as it was considered bad form in England to make people pay for singles that were on albums.
There was a rumor in the Soviet Union that The Beatles had secretly visited the U.S.S.R. and given a private concert for the children of top Communist party members. They believed the song "Back In The U.S.S.R." was written because of the concert. Actually, some fans still believe so.