Year is missing
In-text citations
If your source lacks information about when the document was published, there is a standardized abbreviation for this: (n.d.), meaning “no date”.
Example:
(Foster, n.d.)
In the reference list
Write the entry according to source type. Use “n.d.” instead of year.
Example:
Foster, M. (n.d.). My Life on Earth. Tellus Publishing.
EndNote
Add according to type of source. In the field Year, write: n.d.
Zotero
Add according to type of source. Leave the field Date blank, and Zotero will automatically add n.d.