When read_bibliography tries to read a Pubmed file with only one reference in it, it returns "unknown reference delimiter." The cause of the issue is that a reference list downloaded from Pubmed with only one reference in it has no "ER -" delimiter at the end of the file. Adding a new line with "ER -" to the end of the file resolves the issue. Here is an example file: pubmed-27069645.txt.
When read_bibliography tries to read a Pubmed file with only one reference in it, it returns "unknown reference delimiter." The cause of the issue is that a reference list downloaded from Pubmed with only one reference in it has no "ER -" delimiter at the end of the file. Adding a new line with "ER -" to the end of the file resolves the issue. Here is an example file: pubmed-27069645.txt.