Data in iCite is updated monthly so may lag other sources like PubMed. The updating process begins on the last Thursday of the calendar month and runs over the weekend.
The search on the website queries the PubMed API and citation data comes from the NIH Open Citation Collection which sources from CrossRef, MedLine, PubMed Central, and Entrez. Journals/papers outside of these sources will not be included. Not all citations are included in the OCC, e.g. citations by books and conference posters are not included.