Simplify the following text for a Grade 9 native English-speaking person.
Original: Northanger Abbey and Persuasion , published together posthumously in December 1817 , were reviewed in the British Critic in March 1818 and in the Edinburgh Review and Literary Miscellany in May 1818 .
Simplified: Northanger Abbey and Persuasion were published together in December 1817 . They were reviewed in the British Critic in March 1818 and in the Edinburgh Review and Literary Miscellany in May 1818 .