192
Susan J. Gordon et al. Pillow use: the behavior of cervical stiffness, headache and scapular/arm pain. J Pain Res 2010, PMCID: PMC3004642.
193
The Guardian: Should I throw away my pillows? theguardian.com/lifeandstyle/2014/aug/10/should-throw-away-my-pillows.
194
Sleep Like The Dead: How to choose the right pillow. sleeplikethedead.com/pillow-sleeping-positions.html.
195
UpToDate: Joint protection program for the neck. uptodate.com/contents/joint-protection-program-for-the-neck.
196
Harvard Health Publications: Say «good night» to neck pain. health.harvard.edu/healthbeat/say-good-night-to-neck-pain.
197
National Health Service: Planning your pregnancy. nhs.uk/conditions/pregnancy-and-baby/pages/planning-pregnancy.aspx.
198
National Health Service: Can I get pregnant if I have sex without penetration? nhs.uk/chq/Pages/975.aspx?CategoryID=54&SubCategoryID=128.
199
The Naked Scientists: How fast do sperm swim and how do they find the egg? thenakedscientists.com/HTML/questions/question/2472.
200
Humanae Vitae. w2.vatican.va/content/paul-vi/en/encyclicals/documents/hf_p-vi_enc_25071968_humanae-vitae.html.
201
Mayo Clinic: Basal body temperature for natural family planning.
mayoclinic.org/tests-procedures/basal-body-temperature/basics/what-you-can-expect/prc-20019978.