TY  - DATA
AU  - Skala, Helen.
TI  - Trellis theory
T2  - Memoirs of the American Mathematical Society, 
SN  - 9780821899199 (online)
PY  - 1972///
CY  - Providence, R.I.
PB  - American Mathematical Society
UR  - http://www.ams.org/memo/0121
ER  -