I know that the nested quotes are usually punctuated as follows (British usage):
[...] and then he said: 'I will always remember Churchill's "I have nothing to offer but blood, toil, tears and sweat" as the most powerful quote to ever get me through tough times.'
What quotation mark should be used if that is inserted into yet another quote: eg.
Jules Cocovin gave this precise quote: '[...] and then he said: "I will always remember Churchill's #I have nothing to offer but blood, toil, tears and sweat# as the most powerful quote to ever get me through tough times."'
Please, kindly, refrain from advice regarding how I can restructure the sentence. I know how. I don't know what the 3rd level of quotation marks is in English.