Hey Przem,
Here is the Wikipedia encyclopedia definition:
The whole nine yards or full nine yards is a colloquial American phrase meaning "everything, the whole lot" or, when used as an adjective, "all the way," as in, "The Army came out and gave us the whole nine yards on how they use space systems." Its origin is unknown.
The phrase was introduced to a national audience by Elaine Shepard in the Vietnam War novel The Doom Pussy (1967). Use of the phrase became widespread in the 1980s and 1990s. Much of the interest in the phrase's etymology can be attributed to New York Times language columnist William Safire, who wrote extensively on this question.
I like the novel title "The Doom Pussy". The title reminds me of the photo below.
Hope this helps - Nav