Which religious text was the first to incorporate innovative 'cross-referencing' design in its printed format, with margins specifically designed for comparative study?

Throughout history, religious texts have undergone fascinating design evolutions that reflect both technological advancement and cultural values. From ancient scrolls to modern digital formats, the physical presentation of sacred writings reveals much about how different societies have honored and preserved their spiritual wisdom. This trivia question explores an interesting fact about the innovative product design of one of the world's most influential religious texts.

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The Gutenberg Bible (1455)
The Buddhist Tripitaka Koreana (13th century)
The Islamic Ottoman Mushaf (16th century)
The Hindu Bhagavad Gita Bhasya editions (15th century)