What are Debye potentials?

Dear all,

Happy new year!

I'd like to get a clear concept of Debye potentials.
For the sake of this, I searched around the internet and
checked several classic textbooks, like Jackson's and
Stratton's, but no satisfactory results. Instead I get
several papers describing Debye potentials published
decades before ("Debye potential representation of
vector fields").

From those papers I find out that:
Debye potentials have something to do with the special
case of Helmholtz Theorem with divergenceless vector
fields. It's proved then this field can be represented by
two scalar potentials:
F = Lø + curl(L=÷),
where F is the vector field and L is the standard orbital
angular momentum operator. It's said these two scalar
potentials are Debye potentials. (Is this obsolete? Why
isn't there any like content in today's textbooks)

Except this I also get various descriptions, but I can't
figure out a unified idea. Could anyone suggest some
detailed reading?

BTW, it seems that Debye potentials have close
relation with multipole expansion. Is this true and what's
that?

Thanks for any reply!

.