aspnetcore/build/sources.props

<Project>

  <Import Project="$(DotNetRestoreSourcePropsPath)" Condition="'$(DotNetRestoreSourcePropsPath)' != ''"/>

  <PropertyGroup>
    <RestoreSources>
      $(DotNetAdditionalRestoreSources);
      $(DotNetRestoreSources);
    </RestoreSources>
    <RestoreSources Condition=" '$(DotNetBuildOffline)' != 'true' ">
      $(RestoreSources);
      https://dotnetfeed.blob.core.windows.net/dotnet-core/index.json;
      https://api.nuget.org/v3/index.json;
    </RestoreSources>
    <RestoreSources Condition=" '$(DotNetBuildOffline)' != 'true' AND '$(DisableMyGetRestoreSources)' != 'true' ">
      $(RestoreSources);
      https://dotnet.myget.org/F/dotnet-core/api/v3/index.json;
      https://dotnet.myget.org/F/aspnetcore-tools/api/v3/index.json;
      https://dotnet.myget.org/F/aspnetcore-master/api/v3/index.json;
      https://dotnet.myget.org/F/roslyn/api/v3/index.json;
      https://vside.myget.org/F/vssdk/api/v3/index.json;
      https://vside.myget.org/F/vsmac/api/v3/index.json
    </RestoreSources>
  </PropertyGroup>
</Project>