taxlitigator.me/2019/05/26/a-district-court-enforces-a-john-doe-summons-issued-to-a-law-firm-prefaced-by-a-brief-primer-on-john-doe-summonses-by-robert-s-horwitz/
federaltaxcrimes.blogspot.com/2019/05/district-court-rejects-argument-that.html#more
www.jonesday.com/IRS-Summons-for-Law-Firm-Client-Data-Is-Enforceable-05-28-2019/