The Beatles were never invited to play in Soviet Russia, and their albums were considered a threat - banned long after the likes of The Rolling Stones had records released behind The Iron Curtain.
Contrary to popular belief, it wasn't absolutely impossible to listen to the Beatles in the USSR.
By the 1980s, even the state music company, Melodia, was producing recordings by the group.
But in the heyday of Beatlemania, real vinyl discs were only available on the black market and, even then, they changed hands for very large sums of money.
The cost of one such record could be as high as two weeks' salary for an average Soviet worker.
However, there was also a thriving trade in bootleg discs, produced in the USSR and Eastern Europe.
Vinyl was scarce and expensive, so enterprising retailers sought alternatives. What they discovered was that music could be etched onto x-rays.
Discarded x-ray films were collected (or bought under-the-counter) from Soviet hospitals, and the music was pressed onto them using a modified record player.
The results looked like the flexi-discs you used to get on the cover of Western pop magazines, only with ghostly images of rib cages and broken legs imprinted on the plastic.
Fans called the albums "music on the bones".
But the music had to come from somewhere in the first place, and the Beatles' albums and EPs were most frequently smuggled into the USSR in sailors' and actors' luggage. Sometimes even diplomats and party workers brought them from abroad.
The risks were great. If a colleague saw you with "ideologically alien" music and informed the KGB, you could be barred from travelling abroad.
It was similarly bad news if you were caught selling the discs to eager music fans.
However, despite all these obstacles, the desire to listen to the Beatles was stronger.
Most purchases were arranged in advance over the telephone. However, there were real markets, too.
They sprang up near music shops, community centres (which were called Houses of Culture) and in parks. One famous location was outside a Moscow tube station, where it was easy to blend with crowds and escape the police.
Artemy Troitsky, a well-known Russian music critic and promoter, explains that cost of bootlegged albums depended on where they were produced and on the appetite of the seller.
"English and American vinyls cost a lot," he says. "French and Italian, less.
"Other ones, for example, those produced in Bulgaria, were not expensive at all. A new album by the Beatles could cost 50, 60, 70 roubles. It all depended on how greedy the seller was."
The cost of Beatlemania was high, then. A young engineer in the USSR earned between 120 and 150 roubles a month.
Mikhail Ivanov, who sold vinyl discs in the city of Perm during the Soviet era, says the further you went from Moscow, the more expensive disks became.
"For example, in the Urals a vinyl could cost 200 roubles," he explains.
According to the Russian journalist Andrei Logutkov, production of cassette recordings from the smuggled discs was a bigger business in the Russian city of Orlov than selling the original articles.
When tape recorders became widely available, this led to a real music revolution in the country.
"I bought a tape of Sgt Pepper's from one of my older friends for 60 kopecks," he remembers.
That money was raised "after a week of skipping school breakfasts," he says. "No problem!"
"The White Album cost one rouble. I was pleased to find on it Glass Onion, which I previously heard on a disc on the bones. We found a whole set of such discs at a rubbish dump and immediately went home to listen to them," he recalls.
In big cities - Moscow and Leningrad - real vinyl discs were more common, but they cost a minimum of three roubles.
"If you paid five roubles, you could get a particularly valuable disc," remembers rock-musician Oleg Chilap.
"There was the top George Harrison Album All Thing Must Pass, released in December 1970. It was on three discs in a box. It was the first triple album in history. You could make a recording of it for five or seven roubles."
Relations between the sellers and music lovers were often strained - but they were cut from a similar cloth.
It would have been hard to sell bootleg albums successfully without knowing about music, and cautious traders invented a system of tricks and small tests to make sure their clients were not police informants.
Any potential buyer was tested for their knowledge of rock music. If he did not pass the test, no-one would deal with him.
But traps could be laid in the other direction, too. Sometimes a buyer would hand over half a month's wages, and be given an envelope with the wrong disc.
"This was a common practice," says Troitsky.
"Someone might buy, for example, Here's Little Richard. When the record started playing, he would hear several notes of Tutti Frutti, and then suddenly there was a voice recording, 'So, would you like to hear some American music?'"
If those who sold and bought discs on the black market were caught by police, not only would their precious album be confiscated, but the police would write a letter to their place of work.
If the person was a member of the Communist Party or the Young Communist League (Komsomol), this would have political consequences. So, a student who was a member of the Young Communist League could be expelled from university.
Sometimes, a young " beatnicki" would have records sent to them in the post by relatives living in the West, but the authorities tried to prevent this, too.
A well-known Russian musician Alexander "Fagot" Alexandrov remembers that one such disc was smashed with a hammer en route to Russia.
Yet, many people who supported and reproduced the Soviet system facilitated the expansion of Western rock music. Diplomats, Communist Party workers, and even KGB members were importing music considered ideologically dangerous.
The money they could make trading records probably wasn't enough of an incentive to risk expulsion from the Communist Party.
But they simply could not refuse themselves the pleasure of listening to, let's say, Hard Day's Night after a difficult day in the office.