The National Library of Medicine's PubMed provides a useful Citation Matcher, which may verify or complete a citation with information provided by the user.
CINAHL (Cumulative Index to Nursing and Allied Health Literature) provides a useful Citation Matcher which may verify or complete a citation with information provided by the user. It can be found in the "More” drop down option in the CINAHL blue header bar.
Library staff is also available to verify citations for in-process papers or hard-to-find articles.