How to Call List of Books and Contact Details using Contact WEb Service Version 2 on C# Development

Hi,

As the subject suggest, please check the codes below and let me know which part should i revise so my program will not encounter and error:

WSOD_Contact.Contact prxySrvContact = new WSOD_Contact.Contact();
WSOD_Contact.ContactQueryPage_Input inputContact = new WSOD_Contact.ContactQueryPage_Input();
WSOD_Contact.ContactQueryPage_Output outputContact = new WSOD_Contact.ContactQueryPage_Output();

inputContact.ListOfContact = new WSOD_Contact.ListOfContactQuery();

//Error is encountered on the 2nd line
inputContact.ListOfContact.Contact = new WSOD_Contact.ContactQuery();
inputContact.ListOfContact.Contact.ExternalSystemId.Value = "";
inputContact.ListOfContact.Contact.OwnedById.Value = "";
inputContact.ListOfContact.Contact.CreatedById.Value = "";

//Error is encountered on the 1st line
inputContact.ListOfContact.Contact.ListOfBook = new WSOD_Contact.ListOfBookQuery();