How to search for usage of types in specific assembly in C#

For example, if an assembly references a library that includes many types, how can I use reflection to determine if the assembly uses a specific type in that referenced library.

If my library DLL has

public class LibraryClass1

public class LibraryClass2

but the assembly referencing the DLL only uses LibraryClass1 (such as new LibraryClass1()) and not LibraryClass2, how can I determine that?