Fibonacci Crossword

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Across
  1. 5. Book published in 1220 (8, 10)
  2. 6. Fibonacci's first name
  3. 8. The number system introduced by Fibonacci (5, 6)
  4. 9. Name of Ratio linked to Fibonacci sequence
Down
  1. 1. First name of Emperor who recognised Fibonacci's services to Pisa
  2. 2. Fibonacci's first publication (5, 5)
  3. 3. Shape found in nature which can be generated by the Fibonacci sequence
  4. 4. Area where Fibonacci learnt about different number systems (13, 5)
  5. 7. City of birth