Odata filter using dates in power query

let
    Source = OData.Feed("https://pbox.ops.dyna.com/data/SOH?cross-company=true
        $filter=(ICAN ne '1001000' or '1001001') and PER_I eq ''" 
        &"&$filter=
            SOS ne Microsoft.Dynamics.DataEntities.SS'Canceled'"

Been trying for a while to add a filter here that will only keep orders (PER_Invoice) made in this month(or in the last 30 days) and ones still undefined (1900-01-01).

Help would be greatly appreciated!