The MHRA Style Guide Online
A Handbook for Authors and Editors • Third Edition
From Chapter 9, 'Quotations and Quotation Marks'
Omissions within prose quotations should be marked by an ellipsis (three points within square brackets; see 5.7). Omitted lines of verse should be marked by an ellipsis on a separate line:
I am not covetous for gold,
But if it be a sin to covet honour
I am the most offending soul alive.
It is not normally necessary to use an ellipsis at the beginning or end of a quotation; almost all quotations will be taken from a larger context and there is usually no need to indicate this obvious fact unless the sense of the passage quoted is manifestly incomplete.