%0 Journal Article %A Mauricio A. Escobar Ruiz %A Ernest G. Kalnins %A Willard Miller Jr. %A Eyal Subag %T BĂ´cher and Abstract Contractions of $2$nd Order Quadratic Algebras %J Symmetry, integrability and geometry: methods and applications %D 2017 %V 13 %U http://geodesic.mathdoc.fr/item/SIGMA_2017_13_a12/ %G en %F SIGMA_2017_13_a12