Table 1: HI surface density profiles from the literature. Some of these profiles may suffer from short-spacing problems which would underestimate the flux from HI on larger scales.

Galaxy	Hubble Type	Instrument	R25	Reference
			arcmin.
NGC 925	SAbd	WSRT	10.47	Wevers et al. (1986)
		VLA		Pisano et al. (1998)
NGC 1365	SBb	VLA	11.22	Jorsater & van Moorsel (1995)
NGC 1425	SBb	-	5.75	-
NGC 1637	SAB(rs)c	-	3.98	-
NGC 2541	SAcd	WSRT	6.31	Broeils & van Woerden (1994)
NGC 2841	SAb	WSRT	8.13	Bosma (1981)
NGC 3198	SBc	WSRT	8.51	Wevers et al. (1986)
NGC 3319	SB(rs)cd	WSRT	6.17	Broeils & van Woerden (1994)
NGC 3351	SBb	-	7.41	-
NGC 3621	SAc	-	12.3	-
NGC 3627	SAB(s)b	-	9.12	-
NGC 4321	SABbc	WSRT	7.41	Warmels (1988)
		VLA		Cayatte et al. (1994)
NGC 4414	SAc	VLA	3.63	Thornley & Mundy (1997)
NGC 4496A	SBm	-	3.98	-
NGC 4527	SAB(s)bc	-	6.17	-
NGC 4535	SABc	WSRT	7.08	Warmels (1988)
		VLA		Cayatte et al. (1994)
NGC 4536	SAB(rs)bc	-	7.59	-
NGC 4548 M91	SBb	WSRT	5.37	Warmels (1988)
		VLA		Cayatte et al. (1994)
NGC 4559	SAB(rs)cd	WSRT	10.72	Broeils & van Woerden (1994)
NGC 4571	SA(r)d	WSRT	3.63	Warmels (1988)
NGC 4603	SA(rs)bc	-	3.39	-
NGC 4639	SABbc	WSRT	2.75	Warmels (1988)
NGC 4725	SABab	WSRT	10.72	Wevers et al. (1986)
NGC 6946	SAB(rs)cd	VLA-D	11.48	Tacconi & Young (1986)
NGC 7331	SAb	WSRT	10.47	Bosma (1981)
M 51	SA(s)bc	WSRT	5.61	Bosma (1981)
M 81	SA(s)ab	WSRT	13.46	Cayatte et al. (1994)