Prince Waldemar of Prussia (1889–1945)
Prince Waldemar William Louis Frederick Victor of Prussia( 20 March 1889 at Kiel – 2 May 1945 at Tutzing, Bavaria) was the eldest son of Prince Henry of Prussia and his wife, Princess Irene of Hesse and by Rhine.
Princess Irene of the Netherlands
Princess Irene of the Netherlands (Irene Emma Elisabeth; born 5 August 1939) is the second child of Queen Juliana of the Netherlands and Prince Bernhard of Lippe-Biesterfeld.
In 1964 she made a controversial catholic marriage in Rome to Carlos Hugo, Duke of Parma, for which she forfeited her place in the royal succession.
Since their 1980 divorce, she has espoused left-wing causes, including anti-nuclear campaigning, as well devising a personal philosophy about relations between man and nature.
Carlos Hugo, Duke of Parma
Carlos Hugo, Duke of Parma and Piacenza (8 April 1930 – 18 August 2010) was the head of the House of Bourbon-Parma from 1977 until his death.
Carlos Hugo was the Carlist pretender to the throne of Spain and sought to change the political direction of the Carlist movement through the Carlist Party, of which he was the official head during the fatal Montejurra Incident.
His marriage to Princess Irene of the Netherlands in 1964 caused a constitutional crisis in the Netherlands.
Princess Carolina, Marchioness of Sala
Princess Maria" Carolina" Christina of Bourbon- Parma, Marchioness of Sala( born 23 June 1974), is the fourth and youngest child of Princess Irene of the Netherlands and Carlos Hugo, Duke of Parma, and is a member of the Royal and Ducal House of Bourbon- Parma, as well as of the Dutch Royal Family.
Princess Irene of Greece and Denmark
Princess Irene of Greece and Denmark( born 11 May 1942) is the youngest child and second daughter of King Paul of Greece and his wife Princess Frederika of Hanover.
She is the younger sister of Queen Sofía of Spain and of the deposed King Constantine II of Greece and maternal aunt of Felipe VI of Spain.
Princess Barbara of Prussia
Princess Barbara of Prussia (2 August 192031 May 1994) was the only daughter and elder child of Prince Sigismund of Prussia and Princess Charlotte of Saxe-Altenburg.
She was a great-granddaughter of Frederick III, German Emperor and a great-great-granddaughter of Queen Victoria.
On 17 September 1952 she was legally adopted by her paternal grandmother, Princess Irene of Prussia ("née" Princess Irene of Hesse and by Rhine), a granddaughter of Queen Victoria.
Juliana of the Netherlands
Juliana ; Juliana Louise Emma Marie Wilhelmina; (30 April 1909 – 20 March 2004) was Queen of the Netherlands from 1948 until her abdication in 1980.
Juliana was the only child of Queen Wilhelmina and Prince Henry of Mecklenburg-Schwerin.
She received a private education and studied international law at the University of Leiden.
In 1937, she married Prince Bernhard of Lippe-Biesterfeld with whom she had four children:
Beatrix, Irene, Margriet, and Christina.
During the German invasion of the Netherlands in the Second World War, the royal family was evacuated to the United Kingdom.
Juliana proceeded to relocate to Canada with her children, while Wilhelmina and Bernhard remained in Britain.
The royal family returned to the Netherlands after its liberation in 1945.
Due to Wilhelmina's failing health, Juliana took over royal duties briefly in 1947 and 1948.
In September 1948 Wilhelmina abdicated and Juliana ascended to the Dutch throne.
Her reign saw the decolonization and independence of the Dutch East Indies (now Indonesia) and Suriname.
Despite a series of controversies involving the royal family, Juliana remained a popular figure among the Dutch.
In April 1980, Juliana abdicated in favour of her eldest daughter Beatrix.
Upon her death in 2004 at the age of , she was the longest-lived former reigning monarch in the world.
Princess Irene, Duchess of Aosta
Princess Irene of Greece and Denmark( 13 February 1904 – 15 April 1974) was the fifth child and second daughter of Constantine I of Greece and his wife, the former Princess Sophie of Prussia.
She was a member of the royal families of Greece and Italy.
From 1941 to 1943 she was also officially Queen Consort of Croatia.
Prince Henry of Prussia (1900–1904)
Prince Heinrich of Prussia,( 9 January 1900 – 26 February 1904), was the haemophiliac third son and youngest child of Prince Henry of Prussia and Princess Irene of Hesse and by Rhine, and thus a grandson of Frederick III, German Emperor on his father's side and a great- grandson of Queen Victoria through both his mother and father.
He died aged four.
Princess Margarita, Countess of Colorno
Princess Margarita Maria Beatriz of Bourbon-Parma, Countess of Colorno (born 13 October 1972), is the eldest daughter of Princess Irene of the Netherlands and Carlos Hugo, Duke of Parma, and is member of the Royal and Ducal House of Bourbon-Parma, as well of the Dutch Royal Family.

Question: Where did Princess Irene Of The Netherlands's mother study?
Answer: University of Leiden