Hi to everyone :) Like the topic's title says, I am starting my journey to Bose-Einstein condensate. What I am looking for are some basic introductory papers or materials that deal with derivation of the Gross-Pitaevskii equation on the basic, most elementary level that is possible. I am a undergraduate student and finishing last year of Bachelor degree, so I have only basic knowledge of quantum mechanics, statistical physics and their application in solid state physics, nanoelectronics and photonics. So any advice from all of you is really welcome, and if you know some material that could be useful and if you btw recommend them to me I would be really grateful. PS I was looking for material on derivation of GP equation, but what I have found were only comprehensive and advance theories that deal with second quantisation and are filled with highly rigorous mathematics, which I think is not a starting point for someone like me :(.