Added reference for Q66 of OOP quiz (Ebazhanov#2733)

* Fixed variable names in Q9 for OOP quiz

* Fixed dictation and correct answer of Q34 of OOP

Inside the body of a static constructor, only static members of a class are accessible.

* Fixed Q35 of OOP quiz dictation

* Update object-oriented-programming-quiz.md

* Update object-oriented-programming-quiz.md

* Updated Q62 of OOP quiz

The choices are a copy of Q61 and are thoroughly irrelevant to Q62

* Fixed dictation of a choice in Q65 of OOP quiz

* Added two new questions (Q66, Q67) for OOP Quiz

* Added reference for Q66 of OOP quiz

oop/object-oriented-programming-quiz.md

@@ -532,6 +532,8 @@ public class Tesla extends FlyingCar{}
 public class Honda extends Car{}
 ```
 
+[reference link](https://stackoverflow.com/a/44913313/1573267)
+
 #### Q67. What is the difference between a parameter and an argument?
 
 - [ ] An argument can have many values while a parameter can have only one value.