Creating a "database link" from Oracle to SQL Server Is there a way for Oracle to read from SQL Server?

We are basically trying to read from a SQL Server table and update the information in Oracle. We used to have a database link in Oracle to another Oracle database. 

Now the application is replaced by a new application that runs SQL Server, so we're trying to replicate the same process but now it's Oracle to SQL Server. Hope that makes sense.
The Oracle database server accepts SQL statements that query data stored in several different databases. The Oracle database server with the Heterogeneous Services component processes the SQL statement and passes the appropriate SQL directly to other Oracle databases and through gateways to non-Oracle databases. The Oracle database server then combines the results and returns them to the client.


Database Heterogeneous Connectivity Administrator's Guide

Oracle provides heterogeneous services to query non-Oracle databases like SQL Server. If you need some guidance here are some useful links.

 Connecting to Non-Oracle Data Sources Through Gateways

 How to Set up Third Party Databases Drivers in Oracle SQL Developer

 Heterogeneous Services - Generic Connectivity