Khalifa's book The Shell: Memoirs of a Hidden Observer (Al-Qawqa 'a: Yawmiyat Mutalassis) was his first novel to be published. Joseph Sassoon has described the book as one of the "most powerful" Arabic memories on prison literature.[5] Khalifa has stated that he considers his prison novel to be "a document and a testimony."[6] Arab publishers were initially wary of printing the autobiographical novel, in which the main character, like the author, is imprisoned for thirteen years during Hafez al-Assad’s regime.[7] However, the Franco-Syrian editor Farouk Mardam-Bey stepped in, releasing the book with the French publisher Actes Sud, having been translated into French by Stéphanie Dujols, entitled La Coquille: Prisonnier politique en Syrie.[1][7] A year later the Arabic publisher Dar al-Adab in Beirut published the book in its original Arabic. The book was then translated into English by Paul Starkey and published by Interlink Books.[1] It has also been translated into several other languages, including Italian and Spanish.[8]