Convert NBIB to PDF

NBIB files are specially structured text files saved in ASCII format, and can be opened and modified using any text editor, as these typically allow users to export PubMed Bibliographic Citation Files directly to Adobe Portable Document Format (.nbib to .pdf conversion).

Various text editors, such as for instance Notepad, allow users to view, print or re-save NBIB files to PDF format. 

Alternatively, you could try using one of several citation managers, such as EndNote, which is also capable of importing NBIB files and exporting them in PDF format.