Diplomacy: Theory and Practice, 6th ed. – Online updating pages
Chapter 7: Embassies
p. 105, last para, locally engaged staff: according to an article in The Washington Post of 3 December 2021 (see Furthe reading), Russian embassies and consulates are an exception: they emply no LE staff at all, relying exclusively on Russians.
Khurshudyan, Isabelle and John Hudson, ‘Amid heightened tensions, Russia and U.S. make quiet breakthrough on staffing at Moscow embassy’, The Washington Post, 3 December 2021
Toosi, Nahal, ‘America’s Last Man standing in Moscow’, Politico, 20 February 2022
A very full article on the US Embassy in Russia during the Ukraine crisis, with good links to other articles.