Arbyn M, Herbert A, Schenck U et al. European guidelines for quality assurance in cervical cancer screening: recommendations for collecting samples for conventional and liquid-based cytology. Cytopathology 2007;18:133-9.

Arbyn M, Bergeron C, Klinkhamer P et al. Liquid compared with conventional cervical cytology: a systemic review and meta-analysis. Obstet Gynecol 2008;111:167-77.

Davey E, Barratt A, Irwig L et al. Effect of study design and quality of unsatisfactory rates, cytological classification, and accuracy in liquid-based versus conventional cytology: a systemic review. Lancet 2006;367:122-32.

Karnon J, Peters J, Platt J et al.  Liquid-based cytology in cervical screening: an updated rapid and systematic review and economic analysis. Health Technol Assess 2004;8:1-78. Review.

Lee KR, Ashfaq R, Birdsong GG et al. Comparison of conventional Papanicolaou smears and a fluid-based system for cervical cancer screening. Obstet Gynecol 1997;90:278:84.

National Institute for Clinical Excellence. Guidance on the Use of Liquid-based Cytology for Cervical Cytology. Technology Appraisal No. 69. NICE; 2003.

NHSCSP. Taking samples for cervical screening: a resource pack for trainers.  NHSCSP Publication No. 23 April 2006. Available as http://www.cancerscreening.nhs.uk/cervical/publications/nhscsp23.html

Siebers AG, Klinkhamer PJ, Vedder JE, Arbyn M, Bulten J (2012). Causes and relevance of unsatisfactory and satisfactory but limited by smears of liquid-based compared with conventional cervical cytology. Arch Pathol Lab Med 136;76-83.