http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Periodic solutions of singular Lagrangian systems
1 online resource (xii, 157 pages) : illustrations.
Antonio Ambrosetti, Vittorio Coti Zelati.
Includes bibliographical references (pages [149]-157).
Critical point theory (Mathematical analysis)
Progress in nonlinear differential equations and their applications ; v. 10