[895] Nilson 1907.

[896] Meyer 1825, p. 44.

[897] Lindsay 1856.

[898] Berkeley 1857.

[899] Weddell 1869.

[900] Phillips 1878.

[901] Scott Elliot 1907.

[902] Vallot 1896.

[903] Bitter 1901.

[904] Heere 1904.