[1]
Bony, J.-M., Colombini, F. and Pernazza, L. 2010. On square roots of class C<sup>m</sup> of nonnegative functions of one variable. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE. 9, 3 (Sep. 2010), 635-644. DOI:https://doi.org/10.2422/2036-2145.2010.3.08.