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Clase and Periódica (ClasePeriodica)

Index of Latin American journals in the sciences and humanities

Why select this database?

  • CLASE indexes documents published in Latin American journals specializing in the social sciences and humanities.
  • PERIÓDICA covers journals specializing in science and technology.
  • Offer access to more than 600,000 bibliographic citations from documents published in 2,600 scholarly journals published in the Spanish, Portuguese, French and English languages.
  • Contain information from articles, essays, book reviews, monographs, conference proceedings, technical reports, interviews and brief notes published in journals edited in 24 different countries of Latin America and the Caribbean, as well as from publications that focus on Pan-American issues.

Subjects included

  • agricultural sciences
  • anthropology
  • arts
  • biology
  • chemistry
  • communication science
  • demography
  • economics
  • education
  • engineering
  • exact sciences
  • foreign affairs
  • geo sciences
  • history
  • law
  • library and information science
  • linguistics and literature
  • management and accounting
  • medicine
  • philosophy
  • physics
  • politics
  • psychology
  • religion
  • sociology

Database details

Database name ClasePeriodica
Short database name UNAM
Available on FirstSearch
Sources More than 2,700 journals
Number of records Over 600,000
Coverage Clase: 1975 to present. Periódica: 1978 to present.
Update frequency Updated quarterly
Producer Universidad Nacional Autonoma de Mexico (UNAM)


Index labels and search examples

Use a colon after an index label (for example, au:) when you are not certain of your search terms. Use an equal sign after an index label (au=) for an exact match search. You can search with an index label from any search screen. The information you type overrides any default menu selections. The following examples show sample rather than actual searches.

Search indexes Etiquetas Ejemplos
Keyword kw: absoluta and efecto

[keyword searches the Source Phrase, Subject, and Title indexes]
Resumen ab: escala
Accession number no: CLA0001234
Article type phrase at= articulo

[use to limit other search terms;browse index for available article types]
Autor au: rodriguez
Author phrase au= rodriguez alvaro

[last name first]
Database name phrase ds= clase

Descriptor de: salud
Descriptor phrase de= salud publica
First page pg: 2
Identificador id: logica
Issue is: 7
Language phrase ln= ingles
Fecha de publicación pd: 2002

[browse index for date formats]
Fuente so: gaceta
Source phrase so= gaceta de economia
Número estándar sn: 0325-1926
Asunto su: flexibilidad
Subject phrase su= flexibilidad laboral
Título ti: formacao
Title phrase ti= formacao dos compostos no portugues
Volume vo: 49
Año yr: 1999
Year 2 yy: 2001

Index use and structure

What follows is a list of FirstSearch indexes and the combination of USE and STRUCTURE attributes that can be used to access them.

  1. For any FirstSearch label where multiple USE attributes are listed all the attributes will provide the exact same search result sets.
  2. Any USE attribute that is not marked as a restrictor is available via the SCAN service.
  3. Restrictors are specially implemented indexes and are not available for scanning. Terms for these must be ANDed with other terms to limit the size of the result set. See the table provided for each restrictor to determine valid terms and their associated meaning.

FirstSearch Indexes and USE and STRUCTURE attributes used to access them:

Índice Descripción Atributo de uso Estructura Atributo Indexed Fields and Subfields
Palabra clave (kw) Cualquier 5110 2 245/a





Keyword All (ka) Cualquier 1016 2 100/a









Abstract (ab) Resumen 62 2 520/a,e,p
Accession Number (no) Control number-local 12 2 035/a
Article Type Phrase (at=) Content-type 1034 1 949/L
Author (au, au=) Author-name 1003 1,2,101 100/a



Author Affiliation Author Affiliation 5100 2 100/u

Corporate Author Phrase (co=) Corporate Author Phrase 1005 1 110/a

Descriptor (de, de=) OCLC Defined 5650 1,2 650/a
Database Name Phrase (ds=) OCLC Defined 5988 1 904/p
First Page (pg) OCLC Defined 5006 2 949/f
Identifiers (id) Subject-local 29 2 653/a

Issue (is) OCLC Defined 5004 2 949/b
Language Phrase (ln=) Code-language 54 1 546/a
Publication Date (pd) Date 30 2 949/e,g
Standard Number (sn) Identifier-standard 1007 2 773/x
Source (so, so=) Title-host-item 1033 1,2 773/t
Subject (su, su=) Asunto 21 1,2 650/a


Title (ti, ti=) Título 4 2 245/a
Volume (vo) OCLC Defined 5013 2 949/a

Record display information

List of FirstSearch fields for ClasePeriodica and the MARC fields to which they correspond:

Nombre del campo Campo(s) MARC
Año 008<date>
Standard SICI Code 024/a
Accession Number 035/a
Language of Abstract 041/b
Autor 100/a

Corporate Author 110/a

Author Affiliation 100/u

Título 245/a
Number of Bibliographic References 504/b
Resumen 520/a,e,p
Idioma 546/a
Subject Added Entry, Topical 650/a
Identifier (Spanish) 653/a
Country of Publication 773/c
Citation 773/g
Host Item Entry 773/t
ISSN 773/x
URL to External Website or Link to Full Text Article (Direct Article Access) 856/u
URL for UNAM's Document Delivery Service Center 902/i
Nombre de la base de datos 904/p
Library Holdings 948

Detailed holdings information is available in FirstSearch Z39.50 Configuration Guide - Element Set Names.
Número de volumen 949/a
Issue Number 949/b
Números de página 949/c
Supplement 949/d
Date 949/e
First Page Number 949/f
Marketing Defined Date 949/g
Julian Day 949/j
Article Type 949/L
OCLC Record Display Type 949/x
Identifier (English) 954/a
Article Focus 954/b


The following restrictors can be used only in conjunction with an index search. They must be added to an index search with the Boolean AND to receive results:

Restrictor Tipo Input Atributo de uso Estructura Atributo
Year* All years

Single year

Range of years

19xx, 20xx

19xx - 20xx
31 5
Database Name Phrase* All




5988 1
Limit to Full Text Limit to full text


full text

6002 2
Limit to Holdings OCLC Institution Symbol Enter symbol for OCLC institution 56 2

* Both an index and a restrictor.

Note: To find the OCLC symbol for an institution, please see the online version of OCLC Participating Institutions.


Search results in the ClasePeriodica database can be sorted by Author (1003), Title (4), Source (1033), and Publication Date (30).

General punctuation rules

Exceptions are made, but these are generally correct:

Punctuation Rule Punctuation Rule
" Delete and collapse $ Delete and collapse
' (apostrophe) Delete and collapse % Delete and collapse
. (period) Delete and collapse * Delete and collapse
, (comma) Delete and collapse + Delete and collapse
; Delete and collapse > Delete and collapse
: Delete and collapse < Delete and collapse
() Delete and collapse @ Delete and collapse
<> Delete and collapse ? Delete and collapse
{} Delete and collapse -- Delete and collapse
[] Delete and collapse / Substitute a space
= Delete and collapse - Retain and index
! Delete and collapse & Retain and index
# Delete and collapse

Searching tips

Keyword All searches (1016): The Keyword All search finds information in these fields: Author (100/a, 700/a); Abstract (520/a,e,p); Source (773/t); Standard Number (773/x); Subject (650/a, 653/a, 954/a); Title (245/a) and Year (964/x).

Using limiters: You can limit searches by Year (31), Database Name Phrase (5988) and Library Holdings (56). Limit to Full text (6002) is used to limit to full text from other databases. Full text availability is dependent upon your institution's access arrangements.

Copyright information

Copyright © UNAM. All Rights Reserved.