1. Resources can be searched and viewed in the foreground, and data tables can be added, deleted and changed in the background. If security is considered, pdf is best stored in the warehouse.
2. I like Baidu Library. Personally, I think it is better to load PDF files with FLASH, so that the client can save some things.
Finally, I will give you a hint. It's really a good choice for you to choose a resource in PDF format. If you download any other resources and want to convert them into PDF format, the best way is to install a "TinyPDF" virtual printer software, and use the printer to export any files into PDF. After the installation, if you want to convert any resource file, just click on the article and you can save it as a PDF, which can be said to be converted into a 99% distorted PDF.