Sometimes it can be a challenge finding suttas, even if we have an exact citation. Here are some resources to help you out.
Some of the most confounding citations are the ones that use the Pali Text Society (PTS) Pali edition page numbers as a numbering system. You can recognize these citations because they are made up of a letter abbreviation for the book (such as M or MN) a roman numeral indicating the volume (usually, but not always lower case) and then an arabic numeral indicating the page (sometimes followed by another arabic numeral indicating the line). But the handy converter at pts.dhamma-dana.de makes it easy. Just plug in those parts and it give you a link to the sutta it is referring to.
Pāli Suttas Name Index
Know the name of the sutta you are looking for? Kind of know the name? Then you will want to use the wonderful index set up by Bhante Ānandajoti at ancient-buddhist-texts.net. You don’t even need to use the exact diacritics. While you are on the site, be sure to check out the great sutta translations there.
Dictionary of Pali Proper Names (DPPN) Online
Know the name of someone in the sutta you are looking for? Then the DPPN could help. As a printed book, this amazing resource by G. P. Malalasekera takes up more than 6 inches of shelf space. Fortunately it is available in an easy to use format online. The citations are all in the PTS format, so you may need to use the converter found at the top of this article. It is extremely comprehensive, even including people found only in the commentarial literature.
Topic, Simile and People Indexes
Often we will know the topic of what we are looking for, but nothing else. Unfortunately there are only limited online resources for looking up suttas this way.
AccesstoInsight.org has these indexes, but they are only for suttas on their site. SuttaCentral.net has adapted these indexes, but not expanded them to cover the whole site. SuttaFriends.org has similar indexes, but again, their site is still rather limited.
If you just need an alphabetical listing of jātaka stories in the Pali Canon, there is a simple list here on ReadingFaithfully.org. But for a more detailed search, try the database at the University of Edinburgh. If you want to only find stories from the Pali tradition, be sure to select “Jātakatthavaṇṇanā.”
Sometimes none of these methods work and we just have to reach out for help. Both the SuttaCentral discussion forum and the DhammaWheel forum are good places to post requests for help finding a sutta. On SuttaCentral, use the “General” category, and on DhammaWheel, post to the “General Theravāda discussion” subforum. Remember to give a good descriptive title to your post, not simply “Need help finding sutta”