ADS currently receives abstracts or tables of contents from almost two hundred journal sources. The service may receive data referring to the same article from multiple sources, and creates one bibliographic reference based on the most accurate data from each source. The common use of TeX and LaTeX by almost all scientific journals greatly facilitates the incorporation of bibliographic data into the system in a standardized format, and importing HTML-coded web-based articles is also simple. ADS utilizes Perl scripts for importing, processing and standardizing bibliographic data.