Chapter in Book

@BOOK{B:Sagias_1_2007,
AUTHOR = {Nikos C. Sagias and et al.},
TITLE = {Digital Satellite Communications, Theoretical Background (Chapter 3)},
PUBLISHER = {Springer},
YEAR = {2007},
address = {USA},
month = {Jan.},
doi = {10.1007/978-0-387-34649-6}
};

@BOOK{B:Sagias_2_2007,
AUTHOR = {Nikos C. Sagias and et al.},
TITLE = {Digital Satellite Communications, Modulation Techniques (Chapter 6)},
PUBLISHER = {Springer},
YEAR = {2007},
address = {USA},
month = {Jan.},
doi = {10.1007/978-0-387-34649-6}
};