Symbol in Alan Turing's On Computable Numbers

[Bluskyz]

In Alan Turing's On Computable Numbers, he explains in his second paragraph the general notion of computable numbers. In doing so, he writes "In [symbol][symbol] 9, 10 I give some arguments...". I will include a screenshot of these symbols in this post. Do any of you know what these symbols mean? I guessing they are just some way of citing his paper "9, 10" which I also have no idea of. He uses this notation throughout the paper so if you happen to know the papers he is referring to, please enlighten me. Thank you.

 

[jedishrfu]

It's a double s

http://en.m.wikipedia.org/wiki/Section_sign

 

[jtbell]

He's just saying (in shorthand notation) "In sections 9 and 10 I give some arguments..." Presumably these are sections of the same book, unless he refers explicitly to a different book.