@Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final LibraryMaterial other = (LibraryMaterial) obj;
        if (!Objects.equals(this.author, other.author)) {
            return false;
        }
        if (!Objects.equals(this.title, other.title)) {
            return false;
        }
        if (this.publicationYear != other.publicationYear) {
            return false;
        }
        return true;
    }