”Historical Outline”, The Mercator Projections – The Normal and Transverse Mercator Projections on the Sphere and the Ellipsoid with Full Derivations of All Formulae, s. 15–16. Edinburgh: Peter Osborne, 2013. Teoksen verkkoversio (PDF). (Arkistoitu – Internet Archive)
”Historical Outline”, The Mercator Projections – The Normal and Transverse Mercator Projections on the Sphere and the Ellipsoid with Full Derivations of All Formulae, s. 15–16. Edinburgh: Peter Osborne, 2013. Teoksen verkkoversio (PDF). (Arkistoitu – Internet Archive)