@article{700212,
     title = {Some applications of the second method of Liapunov to dynamical systems described by partial differential equations},
     booktitle = {Differential Equations and Their Applications},
     series = {GDML\_Books},
     publisher = {Slovensk\'e pedagogick\'e nakladate\v lstvo},
     address = {Bratislava},
     year = {1967},
     pages = {281-287},
     mrnumber = {MR0249799},
     zbl = {0186.16406},
     url = {http://dml.mathdoc.fr/item/700212}
}

Parks, P. C. Some applications of the second method of Liapunov to dynamical systems described by partial differential equations, dans Differential Equations and Their Applications, GDML_Books,  (1967), pp. 281-287. http://gdmltest.u-ga.fr/item/700212/