You are given three tables, named articles, citing_cited, and article_author.

The articles table contains the following columns:
- article_id (String): the unique identifier of the article;
- article_title (String): the title of the article;
- title_word_count (Integer): the number of words in the article's title (using spaces to determine word boundaries);
- author_count (Integer): the number of authors for the article;
- reference_count (Integer): the number of references cited in the article.

<table-articles>

The article_author table contains the following columns:
- relation_id (String): the unique identifier of the article-author relationship;
- article_id (String): the identifier of the associated article;
- author_name (String): the name of the author;
- author_position (Integer): the position of the author in the author list (starting from 0 for the first author).

<table-article_author>

The citing_cited table contains the following columns:
- relation_id (String): the unique identifier of the citation relationship between two articles;
- article_id_citing (String): the identifier of the article which cites the other article;
- article_id_cited (String): the identifier of the article which is cited by the other article.

<table-citing_cited>


Based on the information in the tables above, answer the question provided below.

If the answer consists of multiple components (e.g., author names, article titles, reference counts), separate them with commas.
For example, if the answer includes two author names, your response should be in the format of 'the-first-author-name, the-second-author-name'.

Think step by step, and place your final answer within \boxed{}. If you cannot get the answer from the tables, just return 'NULL'.

Question:

<question>
