Kimberling, Clark (1994), «Central Points and Central Lines in the Plane of a Triangle», Mathematics Magazine67 (3): 163-187, JSTOR2690608, MR1573021..
Edmonds, Allan L.; Hajja, Mowaffaq; Martini, Horst (2008), «Orthocentric simplices and biregularity», Results in Mathematics52 (1-2): 41-50, MR2430410, doi:10.1007/s00025-008-0294-4, «It is well known that the incenter of a Euclidean triangle lies on its Euler line connecting the centroid and the circumcenter if and only if the triangle is isosceles»..
Edmonds, Allan L.; Hajja, Mowaffaq; Martini, Horst (2008), «Orthocentric simplices and biregularity», Results in Mathematics52 (1-2): 41-50, MR2430410, doi:10.1007/s00025-008-0294-4, «It is well known that the incenter of a Euclidean triangle lies on its Euler line connecting the centroid and the circumcenter if and only if the triangle is isosceles»..
Kimberling, Clark (1994), «Central Points and Central Lines in the Plane of a Triangle», Mathematics Magazine67 (3): 163-187, JSTOR2690608, MR1573021..