(I have tried to draw attention to the most accessible books and articles. For full details of all works cited, see the Bibliography.)
Most general histories of English have been consulted. Baugh and Cable (1993, 4th edn) is a standard work by an American scholar; it has been valuably up-dated on contemporary varieties. A very readable introduction is Barber (1972, 5th edn); Bolton (1967) is short and very clear. McCrum et al (1986) is lively and accessible but with a highly literary perspective; Burnley (1992a) is a detailed textual history of the traditional kind. More difficult, but infinitely rewarding are Strang (1970) and Samuels (1972). The Cambridge History of the English Language (General Editor R. Hogg) is authoritative and highly detailed (1992-). Partridge (1969), Barber (1976), Blake (1977) and Görlach (1991) are invaluable studies of particular periods, as from a more critical and political perspective are Smith (1984) and Crowley (1989). A very useful collection of essays is edited by Lass (1969). Histories of English that have been more clearly influenced by sociolinguistics are Bailey (1991) and Milroy (1992a); Machan and Scott (1992) is a useful collection of chapters on the history of English world-wide; Graddol et al (1996) deals with variation and change from a largely sociolinguistic perspective.
I have used the standard sociolinguistics introductions. A recent and clear one is by Hudson (1980), but the beginner might best start with Trudgill (1974b). A more recent one in Romaine (1994). Bell (1976) is a handy reference book. Two collections of essays are now regarded as classics: Giglioli, and Pride and Holmes (both 1972).
The notion of 're-tribalisation' is taken from Khlief (1979). For multilingualism in contemporary England, see Edwards (1979), Rosen and Burgess (1980) and the Linguistic Minorities Project (1985); for the study of linguistic history, see Bynon (1977); Romaine (1982).
A stimulating starting-point is Haugen (1966). See also Stewart (1968). For diglossia, see Ferguson (1959); for bilingualism, Hornby (1977); Romaine (1989); pidgins and creoles, Todd (1974, 1984); Romaine (1988).