1) The first comes from Recueil des parties du championnat du monde (Alekhine-Euwe) 1935, (Brussels, undated). The introduction to the 28th game (page 82) strongly suggests that Klein’s status as Alekhine’s “trainer” was unofficial>

<2) Hans Kmoch, in his Tagebuch vom Wettkampf Aljechin-Euwe (Vienna 1936), does not mention Klein by name but does refer to an incident during the 28th game in which a young chess master was asked to leave the playing-hall. The result was physical violence and police intervention. On pages 70-71 Kmoch wrote [...]>

<‘An unpleasant incident during the 28th game of the Euwe-Alekhine match

During this very important (given the current situation of the match) game an unpleasant incident occurred.

It is known that the world champion has been analysing lately with the young Viennese master Ernest Klein, who is representing several foreign papers as a journalist and is therefore attending the match. In Friday’s game in this city [The Hague – the 27th match-game] Alekhine played, at Klein’s instigation, the Vienna Opening. This he is fully entitled to do. Euwe consults with Flohr and Maróczy. However, that happens outside the playing-room and not while a game is being played.

It seems that yesterday evening Alekhine consulted with Klein, who had just previously told other press representatives that the world champion was playing a variation analysed with him.

Klein was not sitting at the press-table; he had taken his seat in the area reserved for officials. During play, Alekhine, who became more and more excited – he smiled several times – went to Klein on more than one occasion and talked to him, and when he had entered the middle-game with a good position he shook hands warmly with Klein.

One of the Committee members pointed out to the Viennese master that it is improper to talk to a player during the game. If Klein would not stop doing so, the Committee member added, the Committee would have no option but to expel him from the playing-hall and forbid him access to the other games.

Klein protested that he could not stop the world champion talking to him.

As a result, he was told to leave the room and to hand in his press-card. This request he answered by slapping the official’s face, after which the police became involved.

Mr Klein’s conduct is clearly not correct, so we can – as far as we are able to judge from the facts – understand the Committee’s reaction.

However, there is one matter that we do not understand. Should not the Committee have first informed the world champion of his incorrect behaviour? Even if not a word was spoken about the game, Dr Alekhine should have prevented anyone from thinking otherwise.’>

<Benzol>,
According to the "Encycploedia of Chess" by Anne Sunnucks:

"Klein disappeared from the chess scene after a dispute with the British Chess Federation following his withdrawal from a radio match against O Barda of Norway".

Here is the game in question:

One quote: