The ultimate goal is to be concise and to cite what is most useful to the reader. For quotations from a poem in a print or online source, there are three common possibilities:

1. If the poem is short (no longer than a page or its online equivalent), do not cite any number in the text. The page number or web location that appears in the poem’s works-cited-list entry will be specific enough to identify a borrowing from such a short text.
2. If the poem is longer than a page (or its online equivalent) and is published with explicit numbers marking lines or other parts (e.g., stanzas, cantos, books), cite the line numbers and other part numbers but not page numbers. If lines alone are numbered, use the form “line 57” or “lines 119–20” in the first citation, and cite the line numbers alone, without the label line or lines, in the later citations. If other parts are numbered as well as lines, combine the numbers without a label. For instance, if books and lines are numbered, “9.19” means book 9, line 19.
3. If the poem is longer than a page and is not published with explicit numbers marking lines or other parts, cite page numbers (as you would for a work in prose) if the poem is in print. If no page numbers are present (as is often the case online), none can be cited.