Παραπομπή σε μορφή APA (7η εκδ.)

Olum, P. (1961). Invariants for effective homotopy classification and extension of mappings. American Mathematical Society.

Παραπομπή σε μορφή Chicago (17η εκδ.)

Olum, Paul. Invariants for Effective Homotopy Classification and Extension of Mappings. Providence, R.I.: American Mathematical Society, 1961.

Παραπομπή σε μορφή MLA (9th εκδ.)

Olum, Paul. Invariants for Effective Homotopy Classification and Extension of Mappings. American Mathematical Society, 1961.