Task: Question Answering
Input (English): Passage: A number of factors led to the popularity of Netherlandish illuminators. Primary was the tradition and expertise that developed in the region in the centuries following the monastic reform of the 14th century, building on the growth in number and prominence of monasteries, abbeys and churches from the 12th century that had already produced significant numbers of liturgical texts. There was a strong political aspect; the form had many influential patrons such as Jean, Duke of Berry and Philip the Good, the latter of whom collected more than a thousand illuminated books before his death. According to Thomas Kren, Philip's "library was an expression of the man as a Christian prince, and an embodiment of the state – his politics and authority, his learning and piety". Because of his patronage the manuscript industry in the Lowlands grew so that it dominated Europe for several generations. The Burgundian book-collecting tradition passed to Philip's son and his wife, Charles the Bold and Margaret of York; his granddaughter Mary of Burgundy and her husband Maximilian I; and to his son-in-law, Edward IV, who was an avid collector of Flemish manuscripts. The libraries left by Philip and Edward IV formed the nucleus from which sprang the Royal Library of Belgium and the English Royal Library.Netherlandish illuminators had an important export market, designing many works specifically for the English market. Following a decline in domestic patronage after Charles the Bold died in 1477, the export market became more important. Illuminators responded to differences in taste by producing more lavish and extravagantly decorated works tailored for foreign elites, including Edward IV of England, James IV of Scotland and Eleanor of Viseu. 
Question: What were the full names of the two people whose libraries they left formed the nucleus from which sprang the Royal Library of Belgium?
Output (English): Edward IV.