@article {502,
	title = {The Effects of Low Ph and Aluminum on Breeding Success in the Frog Rana-Temporaria},
	journal = {Journal of Herpetology },
	volume = {26},
	year = {1992},
	pages = {353-360},
	author = {Beattie, R.C. and Tyler-Jones, R.}
}
@article {505,
	title = {The Effects of pH, Aluminum Concentration and Temperature on the Embryonic-Development of the European Common Frog, Rana- Temporaria},
	journal = {Journal of Zoology},
	volume = {228},
	year = {1992},
	pages = {557-570},
	author = {Beattie, R.C. and Tyler-Jones, R. and Baxter, M.J.}
}
@article {503,
	title = {A Field-Study of Fertilization and Embryonic Development in the Common Frog (Rana-Temporaria) with Particular Reference to Acidity and Temperature},
	journal = {Journal of Applied Ecology },
	volume = {28},
	year = {1991},
	pages = {346-357},
	author = {Beattie, R.C. and Aston, R.J. and Milner, A.G.P.}
}
