EE promotion was a thing via local clubs for kids (aka future workforce to build missiles). But the choice of components those clubs had was limited, so if you find a schemtics for some cool device in "Radio" magazine chances are you won't be able to find all components for it in such club. This sometimes was even mentioned in the article itslef - like you need this transistor which is not available to general public, but "we all know where to get it ;)"