복소 이차 수체 가 class number 1인 경우 즉 그 정수집합이 UFD가 되는 경우는 다음 9가지가 있음.
1966-67년 스타크와 베이커에 의해 증명됨
Primes of the Form x2 + ny2 : Fermat, Class Field Theory, and Complex Multiplication
The book of numbers
Gauss' class number problem for imaginary quadratic fields
Heegner Points: The Beginnings
The class number of quadratic fields and the conjectures of Birch and Swinnerton-Dyer
Class-Numbers of Complex Quadratic Fields
On the class number of imaginary quadratic fields
There is no Tenth Complex Quadratic Field with Class-Number One
On the imaginary quadratic corpora of class number one