@book{27372,
	author = {Tromp. Solco Walle.},
	title = {On the mechanism of the geological undulation phenomena in general and of folding in particular and their application to the problem of the "Roots of mountains" theory,},
	publisher = {A.W. Sijthoff's uitgeversmaatschappij N.V.,},
	year = {1937.},
	address = {Leiden.}
}