¤ Hamid Zarrabi-Zadeh:  Prayer Times Calculation
 
Historiskt
¤ J. L. Berggren: Episodes in Mathematics of Medieval Islam , Springer, 2003, ISBN 0387406050, 9780387406053
¤ Julio Samsó: Astronomical Observations in the Maghrib in the Fourteenth and Fifteenth Centuries, Science in Context (2001), 14:165-178 Cambridge University Press (abstract)

Fatawa
¤ sunnipath.com - Is Isha not Obligatory in the Summer in UK?
¤ sunniport.com - Masabih (Isha ikhtilaf in the Hanafi madhhab), (alternate link)
¤ muftsays.com - Not allowed to read Isha before time
¤ Dar al-Ifta al-Misriyya, Fatwa No. 20070 (Isha ikhtilaf, all madhhabs, in Arabic)
¤ ISNA recomendation on Fajr angle
¤ Fatwa by Sheikh Ibn 'Uthaymin on Isha at persistent twilight
¤ MWL 1996 statement - translation to English
¤ MWL 2003 and 2007 statement (doc), alernative link (pdf)

Islamiska bönetidtabeller
¤ ICOP Accuate Times: Beräkningsprogram
¤ IslamicAcademy: Tabeller för några svenska städer
¤ Islamiska Förbundet Tabeller för strörre svenska orter
¤ Islamic Finder: Beräkning för valfri ort
¤ Hizb al-Ulama, Blackburn - Y. Miftahi: Salat Times & Qiblah Guide for Towns and Cities in the United Kingdom (alternate link)

Islamiska bönetider under perioder av ständig skymning
¤ ICOP report to MWL meeting 2009, aternative link
¤ The Cambridge Prayer Timetable Project, 2004, (alternate link)
¤ Haitham Al-Haddad: Isha & Fajr Prayer Times During the Summer (diskussion av olika fatawa om ständig skymning)
¤ Timetables of Khalid Shaukat (moonsighting.com) - not avialable online, but discussed at Aisha Charitable Support Services Montreal Canada: Explanation of Muslim  Prayer Timing (alternate link)

Om solens upp- och nedgång
¤ SMHI: Om solens upp- och nedgång
¤ Astroalma: Frågor och svar om solens upp- och nedgång
¤ U:S. Naval Observatory Definitions
Does Height Above Sea Level Affect on Rise & Set?

Astronomiska data för solens upp- och nedgång
¤ SMHI: Solens upp- och nedgång (väderkartan)
¤ Solens upp- och nedgång idag på några orter i Sveige
¤ Astronomisk almanacka
¤ U.S. Naval Observatory: Solens upp- och nedgång vid valfri tid och ort
¤ Astronomical Almanac

Refraktion och atmosfäriska förhållanden
¤ srrb.noaa.gov - Astronomicla glossary: Refraktion
¤ Sampson: Astronomical refraction and the equinox sunrise, J. Roy. Astron. Soc of Canada, 94: 26 — 29, 2000 (alternate link)
¤ Sampson, Lozowski, and Machel: Variability of observed low-altitude astronomical refraction (LAAR) from different geographic locations: progress toward a global map of LAAR variability (abstract), Appl. Opt. 44, 5652-5657 (2005) (astract)
¤ Sampson et.al.: Variability in the Astronomical Refraction of the Rising and Setting Sun (Edmonton), Astronomical Society of the Pacific, 115:1256–1261, 2003 (alternate link)
¤ Young: Sunset Science IV. Low-altitude refraction, The Astronomical Journal, 127:3622–3637, 2004 (alternate link)
¤ Gutierrez Physically-based behavior of light in the atmosphere (extreme refraction), (alternate link)
¤ eh2r.com (dedicated to extreme refraction effects) - Illustration of extreme refraktion & Resolute Bay, Canada (Lat. 74)
 ¤ Shah: Study of aerosols in the atmosphere by twilight scattering

Gryning och skymning (Fajr och Isha)
¤ Yallop & Hohenkerk: A note on sunrise, sunset and twilight times and on the illumination conditions during twilight, Particle Physics and Astronomy Research Council 1996 (alternate link)
¤ Abdul Haq Sultan: Sun Apparent Motion and Salat Times, al-Irshaad Vol. 8, 2004 (alternate link)
¤ therevival.co.uk - FAQ on Salah (Prayer), Question 4. (reflecting policy adopted in payer timetables published wolrdwide by Muslim Brotherhood organisations), (alternate link)

Ljusförorening och natthimlens mörker
¤ Cinzano, Falchi & Elvidge: The first World Atlas of the artificial night sky brightness, Mon. Not. R. Astron. Soc. 328, 689–707 (2001) (alternate link)
¤ Cinzano's karta över ljusföreoreningar i världen, (alternate link)
¤ Cinzano: Karta över magnitud för synbara stjärnor i Europa, (alternate link for figure)
¤ Cinzano: Karta över ljuset på natthimlen i Europa, (alternate link to figure)
¤ Patat, Ugolnikov and Postylyakov: UBVRI twilight sky brightness at ESO-Paranal, Astronomy & Astrophysics Manuscript, 2008 (alternate link)
¤ Can you see Orion? - interactive animation to test sky visilbility

Observationer
¤ weatherscapes.com - Twilight phenomena explained, (alternate link)
¤ Yaqub Ahmed Miftahi, Hizbul Ulama, UK: Fajr and Isha times and Twilight (alternate link)
¤ Omar Azfal: Fajr and Isha: when should we pray? (courtesy of the author)
¤ Omar Azfal: Isha and Fajr observations July 2005 (courtesy of the author)
¤ Omar Azfal: Fajr and Isha Observations (courtesy of the author)
¤ www.al.sidq.org - Aisha Charitable Support Services Montreal Canada: Explanation of Muslim  Prayer Timing (with comments on the timetables of Khalid Shaukat) (alternate link)
¤ www.al.sidq.org - Hakeem-Ullah Ghauri: Observations for the Beginning of Fajr and Setting of Shafaq (in English) (in Urdu) (courtesy of the author)