Cita APA (7a ed.)

Kostov, V. (1988). The Bulgarian umbrella: The Soviet direction and operations of the Bulgarian secret service in Europe (1. publ.). Harvester [u.a.].

Cita Chicago Style (17a ed.)

Kostov, Vladimir. The Bulgarian Umbrella: The Soviet Direction and Operations of the Bulgarian Secret Service in Europe. 1. publ. Hemel Hempstead [u.a.]: Harvester [u.a.], 1988.

Cita MLA (8a ed.)

Kostov, Vladimir. The Bulgarian Umbrella: The Soviet Direction and Operations of the Bulgarian Secret Service in Europe. 1. publ. Harvester [u.a.], 1988.