  The necessity of this Comment was invoked by numerous mistakes, erroneous
discussions and misleading citations curiously collected in the paper of
F.J.Ernst, V.S.Manko and E.Ruiz and concerning the interrelations between two
integral equation methods developed for solution of Einstein - Maxwell
equations more than twenty five years ago. At first, we clarify the origin of
the errors in the paper of F.J.Ernst, V.S.Manko and E.Ruiz which gave rise to
so curious authors "conclusions" as that the monodromy transform integral
equations "...are simple combinations of Sibgatullin's integral equations and
normalizing conditions..." or even that "...in the electrovac case Alekseev's
integral equations are erroneous...". In the Comment, the way of correct
derivation of Sibgatullin's reduction of the Hauser and Ernst integral
equations in the context of the monodromy transform approach is briefly
outlined. In response to various speculations and priority claims collected in
the section 3 of the F.J.Ernst, V.S.Manko and E.Ruiz paper, the concrete
references are given here to the papers which were ignored completely by these
authors and which show that the so called "extended electrovacuum N-soliton
solutions" considered by E.Ruiz, V.S. Manko and J. Martin in 1995, are not new
because all these solutions are the particular cases of a larger class of
solutions constructed much earlier in explicit (determinant) form using the
monodromy transform equations, and that the real story of construction of the
solution for superposition of fields of two Reissner - Nordstr\"om sources and
of corresponding equilibrium configurations found in our papers with V.Belinski
differs crucially from that, which one can read in the paper of F.J.Ernst,
V.S.Manko and E.Ruiz.
