Springer-Verlag.

NLM (Medline).

Global Science Center LP.

Surgical Society of Kenya.

Elsevier GmbH.

Sciendo. 4.

Association of Clinical Cardiologists.

HSPI.

Korean Society of Coloproctology.

Springer-Verlag GmbH.

Duke University Press.

Medical and Dental Consultants Association of Nigeria, OOUTH Chapter.

Elsevier Espana S.L..