@unpublished {542,
	title = {The Mollusca collected by the University of Michigan-Williamson expedition in Venezuela},
	year = {1930},
	pages = {210: 1-95},
	author = {Baker, H.B.}
}
@unpublished {540,
	title = {The Mollusca collected by the University of Michigan-Walker expedition in southern Vera Cruz, Mexico},
	year = {1922},
	pages = {106: 1-95},
	author = {Baker, H.B.}
}
