I'd go for 'p 24, para 5' or 'p 24, line 11' I don't feel there is any particular need to write 'page' and 'paragraph' in full. I think that it is sufficient to give either the paragraph or the line. If I am citing a book, I normally give only the page (and year of publication) thus: Swan (2005.24)'
Others may feel differently.
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