"Diagram of the Heart" is a photo book by <a href="http://www.glennagordon.com/" target="external">Glenna Gordan</a> about a small but vibrant cottage industry of Muslim women writing romance novels, littattafan soyayya, in Northern Nigeria, a region best known for the acts of terrorist group Boko Haram. Some books are subversive, while others offer fantasies of escape, and tales of the poor girl marrying the rich man. Here, Farida Ado, one of a small but significant contingent of hijab wearing ladies writes romance novels living in conflicted and rapidly Islamicizing Northern Nigeria. Glenna Gordon

Romance books are tied up and packaged at the local market in Kano, Nigeria. Glenna Gordon

Khadija Gudaji works on her novel while laying in bed at her home in Kano, Nigeria. Glenna Gordon

The diagram of a heart drawn on the outside of a school in Kano, Nigeria. Glenna Gordon

Firdausy El-yakub's university has been on strike for weeks, so she spends most of her days reading and dreams of one day becoming a novelist too in Kano, Nigeria. Glenna Gordon

Author, Amina Hassan, poses for a portrait in her home in Kano, Nigeria. Glenna Gordon

Rabi Tale, a romance novelist, with one of her suitors. Glenna Gordon

A bride looks out the window before her wedding. Glenna Gordon

A young wedding guest sits on a couch all dressed up. Glenna Gordon

A bride is taken by her female relatives, of an arranged marriage, to her husband's home on the outskirts of Kano, Nigeria. Glenna Gordon

The wedding Fatiah, of Maryan Nazifi, takes place in Dawakin Tofa, a small town outside of Kano, Nigeria. Glenna Gordon

A bride at a wedding in Kano, stands apart as male and female guests seldom mix in the conservative Islamic northern part of Northern Nigeria. Glenna Gordon

Novels and other books are put together by hand. Glenna Gordon

Women buy novels at a shop run by Jamila Umar, a popular writer, who opened her own stall at the market in Kano, Nigeria. Glenna Gordon

A woman poses for a portrait at the Office of Enlightenment at the Hisbah, the Islamic morality police. Glenna Gordon