Reader’s question: Should you say Frances’ book or Frances’s book?
Answer: This has become a style choice because the experts don’t agree!
I don’t think it matters as long as you are consistent.
The Australian Government style manual
The Australian Government style manual says:
‘For personal names ending in s, the situation is problematic because of the differing ‘rules’ that are variously invoked. One such rule involves the sound of the word: if the possessive inflection is pronounced as a separate syllable, it takes an apostrophe s; if not, the apostrophe alone should be added. The problem is that different people pronounce such possessives differently. Should it therefore be Burns’ or Burns’s? A competing rule has it that names consisting of one syllable always take an apostrophe s (Burns’s), whereas those of more than one syllable take only the apostrophe (Dickens’). Cutting across these practices is the notion that certain time-honoured names ending in s (particularly from biblical and classical sources) take only the apostrophe, whatever their length or pronunciation (Jesus’, Herodotus’).
‘Given this confused situation, the most straightforward course of action is to add apostrophe s to any name ending in s, however long or short it is and however it is pronounced. Thus:
‘Burns’s poems Dickens’s novels Herodotus’s birthplace.’
The Associated Press
On the other hand, The Associated Press (Guide to Punctuation) says:
‘Just add the apostrophe: Achilles’ heel, Socrates’ question, Jesus’ parables, Hercules’ labours, Oedipus’ blindness, Dickens’ characters, Kansas’ flatlands, Moses’ wanderings, Tennessee Williams’ plays, Xerxes’ armies, Yeats’ poems, Keats’ odes.’
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