exporting-data-to-excel-file-in-angular
https://dev.to/ankitprajapati/exporting-data-to-excel-file-in-angular-using-exceljs-k13
Generate PDF using pdfmake
https://github.com/ngdevelop-tech/angular-pdfmake-invoice-generator
client-side-caching-in-angular-8-using-http-interceptor
https://www.c-sharpcorner.com/article/client-side-caching-in-angular-8-using-http-interceptor/
how-to-create-library-in-angular-tutorial
https://www.samarpaninfotech.com/blog/how-to-create-library-in-angular-tutorial/
Tree based implementation using PrimeNG
https://stackblitz.com/edit/primeng-treetable-demo-npxrcp?file=src%2Fapp%2Fapp.component.ts,src%2Fapp%2Fnodeservice.ts,src%2Fassets%2Ffilesystem-lazy.json,src%2Fassets%2Ffilesystem.json,src%2Fapp%2Fapp.component.html
https://subscription.packtpub.com/book/web-development/9781788299572/5/ch05lvl1sec18/expandable-row-groups