How do you filter entities in the API versions 8.1 and before?

I'm currently trying to filter entities by SchemaName and have been unsuccessful. 

In the API documentation Retrieve metadata by name or MetadataId the filtering syntax is listed as such: 

GET /api/data/v9.0/EntityDefinitions(LogicalName='account')

However, when I try and filter by an entity in this way I get the error: 

Bad Request - Error in query syntax

The only difference between my request url and their request url is they are on version 9.0. Is filtering available for earlier versions? When I try to use the version 9.0 I get the error: 

Requested API Version 'v9.0' is not available

Any ideas on why I am getting the filtering error and/or the versioning error? Thank you.