Neue Verbindungen der Lanthanoiden vom Typ [(C₆H₅)₄E]MX₄ · 8 H₂O = P, As; M = La, Ce, Pr, Sm, Eu, Gd; X = Cl, Br) / New Lanthanide Compounds of the Type [(C₆H₅)₄E]MX₄ · 8 H₂O (E = P, As; M = La, Ce, Pr, Sm, Eu, Gd; X = Cl, Br)