Select rows within a date range using an import range statement.
=query(importrange("https://docs.google.com/spreadsheets/d/<PEOPLE_DATABASE>/edit#gid=1208515556","CS People Database!A:Z"),"SELECT * WHERE Col6 = TRUE AND Col14 > date '" & text(E1,"yyyy-MM-dd") &"' AND Col14 < date '" & text(G1,"yyyy-MM-dd") &"' Order by Col14")