Good starting point:

WEMSK: Old Spanish Texts

Archivo del Romancero Menéndez Pidal WWW -- for the study of the Spanish Romancero.

Biblioteca Virtul del Patrimonio Bibliográfico

Cantar de mio cid WWW-- an interactive site at UT Austin

Biblioteca Virtual Miguel de Cervantes WWW

Digital Libraries of Rare Books in Spain WWW

Gonzalo de Berceo WWW

Libro WWW --online books from university presses.

Medieval Iberia WWW 

Medievalismo WWW -- portal for medieval Spanish history

Parnaseo WWW --for online journals and databases, such as full-text online access to LEMIR (Revista de Literatura Española Medieval y del Renacimiento).

PhiloBilblon WWW --a bio-bibliographical database of early Iberian texts

Proyecto sobre el Romancero pan-Hispanic  WWW 

TESEO Bases de Dates de Tesis Doctorales WWW--list of Spanish dissertations since 1976

WESS Iberian Studies Web WWW 

Other online resources

Literature Resource Center UIUC

Writers Directory UIUC

Biography Resource Center UIUC

Feminae: Medieval Women and Gender Index
FRANCIS
Bibliografía de la Literatura Española desde 1980
International Medieval Bibliography
Internationale bibliographie der Zeitschriftenliteratur
Iter
JSTOR
MLA Bibliography
Project Muse
More Indexes

To find print bibliographies in the Library, search the Library Catalog Quick Search using the subject term "Spanish Literature Bibliography" and using the Subject Heading search function.

Cárdenas, Anthony and Charles Faulhaber. Bibliography of Old Spanish Texts (Literary Texts). Bibliographic Series ; no 4. 3rd ed. Madison: Hispanic Seminary of Medieval Studies, 1984.

016.86 F82M1959
Foulché-Delbosc, R. Manuel de l’hispanisant. New York : Kraus Reprint Corp., 1959.

Saez, Emilio and Mercè Rossell. Repertorio De Medievalismo Hispánico (1955-1975). Barcelona: Ediciones El Albir, 1976.

016.86 SI5B1960
Simon Diaz, José. Bibliografia De La Literatura Hispanica. Madrid: 1960-1980.