Scientific collaboration is the social process by which two or more researchers work together sharing their intellectual and ma-terial resources to produce new scientific knowledge. In this paper, a historical overview is made from the beginning of scientific collaboration, considering the factors involved in this process, the danger that the pressure to increase the curriculum contrib-utes to the fragmentation of biomedical research and the role of "invisible colleges". The first-generation of scientific collabora-tion indicators are also listed and described, including the number and rate of co-authored papers, the co-author index or collab-oration index, and the indicators of institutional collaboration.

This paper presents the journal impact factor published by the Journal Citation Reports of the Web of Science, one of the most used bibliometric indicators in the evaluation of scientific activity and also one of the most controversial. We explain the method of calculation, its criticisms and other related indicators, such as the 5-year impact factor and the immediacy index. Other alternative indicators are also described, such as the Eigenfactor, the Scimago Journal and Country Rank, offered by the Scimago group based on data from the Scopus database, and the Source Normalized Impact per Paper, proposed by the Centre for Science and Technology Studies from the University of Leiden, in the Netherlands.

The bibliometric indicators based on the citations are founded on the assumption that the important papers are usually cited, while the irrelevant ones are ignored. The basic assumptions of citation analysis, the method of calculating these indicators, their advantages, drawbacks and limitations are discussed. We also outline strategies in which journal editors and researchers are supported to increase the number of citations and the most cited articles in the journal Acta Pediátrica Española. The most commonly used basic indicators are the number of citations received by a research unit (author, group, institution, country, journal or subject area), average citations per paper, number of papers cited, h-index, indicators based on the h-index and the crown indicator. Among the indicators extracted from the analysis of references, we discuss the cited half-life, the Price index and the isolation index.

The bibliometric indicators of scientific production measure the results of the research, as published in journals or scientific books. The most used indicator is the number of papers published by an author, institution, country, journal or subject area, since it allows to know and to follow the activity from the publications. This paper presents the main bibliometric indicators of scientific production, discusses the normal productivity and fractional productivity and justifies the necessary normalization of the data mined from bibliographic databases. The need to relativize absolute indicators is explained in terms of some variables that influence their development, such as the number of inhabitants, the gross domestic product or the number of projects awarded. Finally, the main limitations of these indicators are discussed.

Bibliometrics is the use of statistical methods in the analysis of a body of literature to reveal the historical development of subject fields and patterns of authorship, publication, and use. The interest aroused by bibliometric studies in the scientific community has been increasing, especially in the biomedical field. The objective of this work has been to address the methodological considerations to be taken into account when preparing a bibliometric study, especially those related to the knowledge of the area to be studied and the national and international bibliographic databases of data origin. The main applications of the bibliometric indicators and several examples related to Acta Pediátrica Española are described, such as the evolution of the number of articles included in Scopus, the ranking of institutions of origin, the network of cowords and some of the indicators offered by Scimago Journal & Country Rank.

Thomson Reuter distributes its databases through the Web of Knowledge, allowing the search in Web of Science (WOS), Current Contents Connect, Proceedings and Journal Citations Reports. Since the year 2004, the Spanish Foundation for Science and Technology (FECYT) provides the Spanish scientific community, research institutes, universities, and other Spanish R&D institutions with WOK access. This paper presents the process and stages that are involved in finding works in Science Citation Index through the Web of Science according to the different options that the database offers (search, advanced search); citations received by a particular author or work (Cited Reference Search) and impact factor and other bibliometric indicators (total times cited for each journal or 5-year impact factor or immediacy index, among others) of the journals that are part of the coverage of the Social Science Citation Index and Science Citation Index in Journal Citation Reports.

Thomson Reuter distributes its databases through the Web of Knowledge, allowing the search in Web of Science (WOS), Current Contents Connect, Proceedings and Journal Citations Reports. Since the year 2004, the Spanish Foundation for Science and Technology (FECYT) provides the Spanish scientific community, research institutes, Universities, and other Spanish R&D institutions with WOK access. This paper presents the process and stages that are involved in finding works in Science Citation Index through the Web of Science according to the different options that the database offers (search, advanced search); citations received by a particular author or work (Cited Reference Search) and impact factor and other bibliometric indicators (total times cited for each journal or 5-Year Impact Factor or immediacy index, among others) of the journals that are part of the coverage of the Social Science Citation Index and Science Citation Index in Journal Citation Reports.