[ref]: https://example.com (bar)
[other-ref]: https://example.com (Shakespeare's "Romeo and Juliet" is a famous play)

[a]: https://example.com "\""
[a]: https://example.com '\"'
[a]: https://example.com (\")

[a]: https://example.com "\'"
[a]: https://example.com '\''
[a]: https://example.com (\')

[a]: https://example.com "\'"
[a]: https://example.com '\)'
[a]: https://example.com (\))

[a]: https://example.com "\\\""
[a]: https://example.com '\\\''
[a]: https://example.com (\\\))

[a]: https://example.com "\\'"
[a]: https://example.com '\\"'
[a]: https://example.com (\\")

[a]: https://example.com "\a\a"
[a]: https://example.com '\a\a'
[a]: https://example.com (\a\a)

[a]: https://example.com "\\a\\a"
[a]: https://example.com '\\a\\a'
[a]: https://example.com (\\a\\a)

[a]: https://example.com "\\\a\\\a"
[a]: https://example.com '\\\a\\\a'
[a]: https://example.com (\\\a\\\a)

[a]: https://example.com "\\\\a\\\\a"
[a]: https://example.com '\\\\a\\\\a'
[a]: https://example.com (\\\\a\\\\a)