APA

(1992). Problems of infectious and parasitic diseases. Sofia: Nat. Center of Infectious and parasitic Diseases.

Chicago

1992. Problems of infectious and parasitic diseases. Sofia: Nat. Center of Infectious and parasitic Diseases.

Harvard

(1992). Problems of infectious and parasitic diseases. Sofia: Nat. Center of Infectious and parasitic Diseases.

MLA

Problems of infectious and parasitic diseases. Sofia: Nat. Center of Infectious and parasitic Diseases. 1992.