At the end of Lemma 2, &quot;[9, Th. 8, (39)]&quot; seems to be referring to corollary 1 of Theorem 8 on page 70 of [1], equation (3.30).  Maybe &quot;(39)&quot; is meant to be &quot;(30)&quot;.<p>Their argument for Theorem 1 seems not-crazy, and quite accessible.<p>[1] <a href="https:&#x2F;&#x2F;projecteuclid.org&#x2F;download&#x2F;pdf_1&#x2F;euclid.ijm&#x2F;1255631807" rel="nofollow">https:&#x2F;&#x2F;projecteuclid.org&#x2F;download&#x2F;pdf_1&#x2F;euclid.ijm&#x2F;12556318...</a>