Kennedy, J. G. (1978). Herbert Spencer. Twayne.
Tohutoru Kātū Chicago (17th ed.)Kennedy, James Gettier. Herbert Spencer. Boston: Twayne, 1978.
Tohutoro MLA (9th ed.)Kennedy, James Gettier. Herbert Spencer. Twayne, 1978.
Kia tūpato: Kāore pea ēnei kupu hautoa i te ōrite pū 100%.