Hi,
Thanks for your response.
If these pdf files are in one folder, we can try to use MSBuild to copy this folder to OutPut directory in Web Deployment project.
To do so, we need to enter Web Deployment project file by right clicking Web Deployment project in Solution Window and selecting "Open Project File", and then write following command below "Import" section:
<Target Name="AfterBuild">
<Copy DestinationFolder="YourDestinationfolder" SourceFiles="YourSourcefile"></Copy>
</Target>
We also can modify your web application's project file to set pdf files to "Content" by
<ItemGroup>
<Content Include="YourFolder\Reference1.pdf"/>
<Content Include="YourFolder\Reference2.pdf"/>
......
</ItemGroup>
Thanks.