Question

What is the meaning of 'et al' in Withers et al (2001)?

Answer 1

It means there is a scientific essay or article published by Withers and his/her friends i.e. coworkers in 2001.

Explanation:

In scientific works (articles, books, etc.) there are reference styles.

This shows "there is a scientific article, book, etc. written by Withers and his/her friends (When you see "et al" you can say this) and this work was published in 2001": et al means that there is more than one author, but the first author is Withers .

Note that for full credit, you need to take a look at the References section of the work which cited Withers et al (2001) in order to see what journal published this study, in addition to Withers, who participated in completing/writing this work, volume and page numbers of the article, etc.