Columbia subject headings:
Critical point theory (Mathematical analysis)--Congresses.
Differential equations, Elliptic--Congresses.
Maxima and minima--Congresses.
Harvard subject headings:
Critical point theory (Mathematical analysis)--Congresses.
Differential equations, Elliptic--Congresses.
Maxima and minima--Congresses.
Princeton subject headings:
Critical point theory (Mathematical analysis)--Congresses.
Differential equations, Elliptic--Congresses.
Maxima and minima--Congresses.