Geodesic
On continuous extension of locally homeomorphic simplicial maps of $\mathbb R^2$ into itself by $\sigma$-processes
Matematičeskie zametki, Tome 59 (1996) no. 6, pp. 821-831 
F. Dell Accio. On continuous extension of locally homeomorphic simplicial maps of $\mathbb R^2$ into itself by $\sigma$-processes. Matematičeskie zametki, Tome 59 (1996) no. 6, pp. 821-831. http://geodesic.mathdoc.fr/item/MZM_1996_59_6_a2/
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     title = {On continuous extension of locally homeomorphic simplicial maps of $\mathbb R^2$ into itself by $\sigma$-processes},
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     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1996_59_6_a2/}
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Voir la notice de l'article provenant de la source Math-Net.Ru

It is shown that the Klein bottle with two points removed can be embedded in the compactification of $\mathbb R^2$ by a finite tree.

[1] Dell' Achchio F., “Kontrprimer k odnoi gipoteze, svyazannoi s problemoi o yakobiane”, Matem. zametki, 58:3 (1995), 452–455 | MR | Zbl

[2] Tsishang Kh., Fogt E., Koldevai Kh.-D., Poverkhnosti i razryvnye gruppy, Nauka, M., 1988