I've been looking online for some training materials which I can collaborate with my own modules for my staff training. One challenge I found was looking for the right link which will let me download materials in their right format (Of course these materials are readily shared and are all acknowledged in my materials.) Personally I prefer downloading materials in PDF form over some html files, a not so easy thing to do actually.
Thank goodness for PDF Search Engine for allowing me make searches for materials according to its formats. This search engine index files according to formats and you can be sure that if you are looking for PDF files, all you get are links offering PDF files!
So you know what to do next time you look for a PDF file.