How to get multiple records from a service using HTTP GET?

Hi experts

    I have a REST based SAP Gateway service. This service has a key field called DeliveryNumber. It returns PGI data for the given Delivery Number.

    It works fine when for one Delivery Number using the below url where '345667' is one delivery number.

    http://xxxxxxxx/getpgidata('345667')

    What I have to do if I want more than one delivery number details? How will my url look?

    For example if I need to get PGI data for DN numbers 12345 and 678989 

    Please help.

Thanks

Gopal