google book https://www.google.com/search?tbm=bks&q=La carta olvidada / The Love Letter (Best Seller)
hathitrust digital library https://babel.hathitrust.org/cgi/ls?q1=La carta olvidada / The Love Letter (Best Seller)&field1=ocr&a=srchls&ft=ft&lmt=ft
The British Library https://bll01.primo.exlibrisgroup.com/discovery/search?query=any,contains,La carta olvidada / The Love Letter (Best Seller)&tab=LibraryCatalog&search_scope=Not_BL_Suppress&vid=44BL_INST:BLL01&lang=en&offset=0
