@startuml
class FixedClock<|-- HSI 
class FixedClock<|-- HSE 
class FixedClock<|-- LSE 
class FixedClock<|-- LSI 
class PLLClock {
-Clock clockSource
}
class USBClock {
-Clock clockSource
}
class SYSClock {
-Clock clockSource
}
class HClock {
-Clock clockSource
}
class PClock {
-Clock clockSource
}
Clock <|.. USBClock
Clock <|.. PLLClock 
Clock <|.. SYSClock 
Clock <|.. HClock 
Clock <|.. PClock 
@enduml