Primary writers:
English:

Julian of Norwich; Margery Kempe; the'Cloud' author; Richard Rolle

Continental:
(mostly women)
 Hildegard of Bingen
 Mechthild of Magdeburg and the other women of Helfta
 Beatrijs of Nazareth
 Johannes Tauler
 Henry de Suso
 St. Bridget of Sweden
 Catherine of Siena
 Margeret d'Oingt
 Marguerite de Porete
 

2.Background and Surveys
a. Anthologies and general studies
*Medieval Women's Visionary Literature ed. E.A. Petroff. (OUP, 1986)
*Medieval Women Writers ed. K.M. Wilson. (Manchester, 1984).
*D. Baker ed. Medieval Women. (Oxford, 1978)
B. Bolton et al. Women in Medieval Society (Philadelphia, 1976)
W. Riehle: The Middle English Mystics (London, 1981)
*P. Dronke: Women Writers of the Middle Ages (Cambridge, 1984)
C. Erickson and K. Casey: 'Women in the Middle Ages: A Working Bibliography' Medieval Studies 37 (1975).
R. Bridenthal and C. Koonz: Becoming Visible: Women in European History. (Boston, 1977)
C. Bynum: Holy Fast and Holy Feast: The Religious Significance of Food to Medieval Women, (Univ. of California Press, 1987)
C. Bynum: Fragmentation and Redemption, (New York: Zone Books) 1991.
M. Erler and M. Kowaleski: Women and Power in the Middle Ages, (Georgia UP 1988)
S. Beckwith, Christ's Body: identity, culture and society in late medieval writings. Routledge, 1993.
Carol Meale, (ed). Women and Literature in Britain 1150-1500, (Cambridge, 1993) especially Felicity Riddy's chapter.

3. Studies of Individual Works
a. Margery Kempe
 D.Aers: Community, Gender and Individual Identity: English Writing 1360-1430. (London, 1988) Ch. 2
chapter in S. Delany: Writing Woman (New York, 1983) Repr. from Minnesota Review 5 (1975): "Sexual Economics, Chaucer's Wife of Bath and Margery Kempe."
*S. Beckwith: "A Very Material Mysticism: The Medieval Mysticism of Margery Kempe." in D. Aers ed. Medieval Literature, Criticism, Ideology and History (Brighton, 1986)
A. Goodman: "The Piety of John Brunham's Daughter of Lynn." in D. Baker ed. Medieval Women. (Oxford, 1978)
C. Atkinson: Mystic and Pilgrim: The Book and the World of Margery Kempe. (Ithaca, New York, 1983)
K. Lochrie: Margery Kempe and Translations of the flesh, (Philadelphia: UPP Press) 1991.
Sandra McEntire, Margery Kempe: A Book of Essays, New York, London: Garland (1992)

b. Julian of Norwich
D. Knowles: The English Mystical Tradition, (London, 1961)
R.K. Stone: Middle English Prose Style: Margery Kemp and Julian of Norwich, (The Hague, 1970)
R.M. Wilson:'Three Middle English Mystics' E&S 9 (1956) 87-112.
B.A. Windeatt: "Julian of Norwich and her Audience' RES 28 (1977)
S. de Beauvoir: The Second Sex, (1949) tr. 1953 chapter on mystics.
Frances Beer, Women and Mystical Experience in the Middle Ages, Boydell 1992. (See review in Medium Aevum 62, 1993  p. 322).

c. Hildegard
S. Flanagan: Hildegard of Bingen: A Visionary Life. (Routledge, 1989)
Hildegard of Bingen: Book of Divine Works with Letters and Songs, (ed.) M. Fox, (Santa Fe: Bear & Co., 1987.)
B. Newman: Sister of Wisdom: St Hildegard's Theology of the Feminine (Berkeley 1987)
Hildegard of Bingen: An Anthology ed. F. Bowie and O. Davies (SPCK 1991)
Beguine Spirituality: An Anthology ed and tr. F. Bowie and O. Davies, (SPCK, 1989)

d. Middle English Translations of Writings by Continental Women
The Book of Gostlye Grace by Mechtilde of Helfte, ed. T. Halligan (Toronto, 1979)
The Liber Celestis of St. Bridget of Sweden. ed. R. Ellis. (EETS 291) 1987.
Margaret Porete: The Mirror of Simple Souls. ed. M. Doiron (Edizioni di Storia e Letteratura, repr. from Archivio italiano per la storia della Pieta V. (almost unobtainable, see relevant chapter in P. Dronke: Women Writers of the Middle Ages.
The Orchard of Syon. ed. P. Hodgson and G. Liegey (EETS 258) 1966. (15c. translation of Catherine of Siena's Dialogue)

Links to:

Julian and other 'Godfriends' site
luminarium Julian site
some medieval mystics
a Margery Kempe site