Gemma Frisius, his method of determining differences of longitude by transporting timepieces (1530) and his treatise on triangulation (1533) / A. Pogo.
Note:
A p. 487-506 ripr. facs. di: Libellus de lo corum describendorum ratione & de eorum distantiis inueniendis nunquam ante hac visus / per Gemmam Phrysium. [Antuerpiae] : Ioan. Grapheus typis cudebat Antuerpiae, 1533
Isis Vol. 22 (1935), p. 469-506