The list of all invoices issued for a supplier can be found in Suppliers/Supplier Details. So, select the supplier from the supplier list, open the supplier and under Operations you may see all invoices issued to that supplier. 

All invoices issued for all suppliers can be found in Supplier Invoices list. Go to Operations from the main left menu and click on Supplier Invoices. You can search for a specific invoice using the search field and search criteria as in below screenshot:

The list of invoices can be sorted out according to your preferences and search fields available.

To see the details of the invoice click on the Supplier Invoice Code displayed in the list.