Given the task definition and input, reply with output. In this task, you're given a statement, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.

Context: In the 10th century, Abd al-Rahman al-Sufi (Azophi) carried out observations on the stars and described their positions, magnitudes, brightness, and colour and drawings for each constellation in his Book of Fixed Stars. Link Information: The Book of Fixed Stars ( ) is an astronomical text written by Abd al-Rahman al-Sufi (Azophi) around 964. Question: How many years of total work did it take Abd al-Rahman al-Sufi (Azophi) to create his Book of Fixed Stars?
Answer: 1