A nice example of how helpful a quick ANNIE search can be. I took the phrase 'day of the dead' and ran it through as a W (keyword) search. 'of' and 'the' are not indexed, but of the 19 items with both 'day' and 'dead' 3 are immediately and obviously useful:
You searched for the KEYWORD: day of the dead W&L CATALOG 19 entries found, entries 1-8 are: LOCATIONS 1 The day of the dead : tradition and change in c LEYBURN 2 Dubliners, LEYBURN 3 Easy in the islands : stories LEYBURN 4 The Egyptian Book of the dead : the Book of goi LEYBURN 5 Halloween and other festivals of death and life LEYBURN 6 Hope should always, stories LEYBURN 7 Innocent blood crying to God from the streets o LEYBURN 8 Joyce: a collection of critical essays, LEYBURN 9 The judgment of the dead: the idea of life afte LEYBURN 10 Let the dead bury their dead : and other storie LEYBURN 11 Names of horses LEYBURN 12 The poetry and voice of Ted Hughes. LEYBURN 13 The powers that prey, LEYBURN 14 Redefining the American Gothic : from Wieland t LEYBURN 15 Selections. LEYBURN 16 The skeleton at the feast : the Day of the Dead LEYBURN 17 The stories of Breece D'J Pancake LEYBURN 18 Todos Santos in rural Tlaxcala : a syncretic, e LEYBURN 19 Xanadu 2 ===== AUTHOR Carmichael, Elizabeth. TITLE The skeleton at the feast : the Day of the Dead in Mexico / Elizabeth Carmichael, Chloe Sayer. EDITION 1st University of Texas Press ed. PUBLISHER Austin : University of Texas Press, 1992. DESCRIPT 160 p., 32 p. of plates : ill. (some col.), map ; 28 cm. NOTE "Published in co-operation with British Museum Press." BIBLIOG. Includes bibliographical references (p. 153-155) and index. SUBJECT All Souls' Day --Mexico. Festivals --Mexico. Dead --Folklore. Mexico --Social life and customs. Leyburn Library GT4995.A4 C37 1992 AUTHOR Hernandez, Joanne Farb. TITLE The day of the dead : tradition and change in contemporary Mexico : Triton Museum of Art, October 28 through November 25, 1979 = El dia de los muertos : su tradicion, su cambio en un Mexico contemporaneo / Joanne Farb Hernandez and Samuel R. Hernandez ; [photography on location, Sam Hernandez ; studio photography, Mike Narciso ; translation, Carmen Garcia] PUBLISHER [Santa Clara, Calif.] : The Museum, [1979] DESCRIPT 45 p. : ill. (some col.) ; 24 cm. NOTE English and Spanish. BIBLIOG. Bibliography: p. 44-45. SUBJECT Dead --Folklore --Mexico --Exhibitions. Leyburn Library GR115 .H47I originally found the next one with another search, though it's number 18 above. The 'tl' in 'Tlaxcala' is the same consonant cluster as in 'Tepoztlan, for a very good reason...
You searched for the KEYWORD: todos santos W&L CATALOG AUTHOR Nutini, Hugo G. TITLE Todos Santos in rural Tlaxcala : a syncretic, expressive, and symbolic analysis of the cult of the dead / Hugo G. Nutini. PUBLISHER Princeton, N.J. : Princeton University Press, c1988. DESCRIPT xv, 471 p. ; 24 cm. BIBLIOG. Bibliography: p. 445-454. NOTE Includes index. SUBJECT Nahuas --Religion and mythology. Indians of Mexico --Tlaxcala (State) --Religion and mythology. All Saints' Day. All Souls' Day. Nahuas --Acculturation. Leyburn Library F1221.N3 N895 1988These sources could be useful if you need some background on the festival which is the setting for the poem.