https://ch.mathworks.com/help/symbolic/sym.legendrep.html
legendreP - Legendre polynomials - MATLAB
This MATLAB function returns the nth degree Legendre polynomial at x.
legendre polynomialsmatlab
https://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=PASCAL7530059896
EXPANSION OF THE MIE PHASE FUNCTION IN LEGENDRE POLYNOMIALS.
of theexpansionmiephasefunction