www.cliffordchance.com/briefings/2018/04/the_us_imposes_sanctionsoncertainrussia.html
www.globaltradeandsanctionslaw.com/
www.out-law.com/en/articles/2018/april/us-extends-russia-sanctions/
home.treasury.gov/news/press-releases/sm0338
See also:
www.srz.com/resources/sanctions-update-venezuela-and-ukraine-russia.html