To search for Guidelines in PubMed:

1) Consider using the word guidelines in your search. For example: community acquired pneumonia guidelines

2) After you've run your search, make sure your Sorted by Display option is set to Best Match.

3) Ideally you want a very recent guideline, so either use the RESULTS BY YEAR histogram and scroll up the dates, or scroll down further on the left-hand filters and select Publication Date: 5 Years. 

4) To focus your search more, still using the left-hand filters, scroll to the bottom of the filter options, select Additional Filters, and under Article Type, select Practice Guideline, then click on Show

5) Hold up, nothing changed! Practice Guideline is now showing in your left-hand filters under Article Type, but you must check the box next to Practice Guideline to apply the filter.

Ideally you've now found your clinical guideline. If not, see the box for Too Many Results, or the box for Too Few Results. 

6) If you did find your guideline, be sure to click on the article title, and once in the article's record, click on Ferris FullText, and also click on Cite for a start to your citation, making sure you select the correct citation style (AMA, APA, or NLM)