Harrington, Cox & Evans (1997) Harrington, J.; Cox, F.; Evans, Z. (1997). "An acoustic phonetic study of broad, general, and cultivated Australian English vowels". Australian Journal of Linguistics. 17 (2): 155–84. doi:10.1080/07268609708599550.
Roach (2004:241–243) Roach, Peter (2004). "British English: Received Pronunciation". Journal of the International Phonetic Association. 34 (2): 239–245. doi:10.1017/S0025100304001768 (inactive 1 December 2024).{{cite journal}}: CS1 maint: DOI inactive as of December 2024 (link)
Mary W.J. Tay (1982). "'The phonology of educated Singapore English'". English World-Wide. 3 (2): 135–45. doi:10.1075/eww.3.2.02tay.
dsae.co.za
Dictionary Unit for South African English (2023). "‖hlala kahle". Dictionary of South African English. Retrieved 2024-04-20.
Dictionary Unit for South African English (2023). "ibandla". Dictionary of South African English. Retrieved 2024-04-20.
englishspeechservices.com
The STRUT vowel in BrE is highly variable in the triangle defined by ə, ʌ and ɑ, see 'STRUT for Dummies'