@BOOK{ Book!D - 100601613,
AUTHOR = "/ Sally Popkorn",
TITLE = "First steps in modal logic",
LIBRARY= "کتابخانه دانشکدگان فارابی (دانشگاه تهران)",
SUBJECT = "Modality (Logic)",
URL = "/book/100601613/First-steps-in-modal-logic/"}