Invoice A/R Account

@operator

This is the code I'm using to get Open Invoices for a specific customer (specified by Internal ID).  The response has everything I need except the A/R account information.  How do I get the A/R Account information to return along with everything else?

           TransactionSearch invoiceSearch = new TransactionSearch();
            SearchMultiSelectField entity = new SearchMultiSelectField();
            entity.@operator = SearchMultiSelectFieldOperator.anyOf;
            entity.operatorSpecified = true;
            RecordRef custRecordRef = new RecordRef();
            custRecordRef.internalId = customerInternalID;
            custRecordRef.type = RecordType.customer;
            custRecordRef.typeSpecified = true;
            RecordRef[] custRecordRefArray = new RecordRef[1];
            custRecordRefArray[0] = custRecordRef;
            entity.searchValue = custRecordRefArray;

            SearchEnumMultiSelectField searchInvoiceField = new SearchEnumMultiSelectField();
            searchInvoiceField.@operator = SearchEnumMultiSelectFieldOperator.anyOf;
            searchInvoiceField.operatorSpecified = true;
            System.String[] invoiceStringArray = new System.String[1];