Welcome to the Medical Heritage Library Search
The purpose of this tool is to allow you to search the full text of one or more items, all at once.
Each page of each book has been digitized and software has been used to extract and index each word that occurs on every page, thus the term "full text".
The MHL searches the full text and the descriptive information (metadata) compiled for each item (such as title, author, publication date, and subject terms).
As with any digitization project, an OCR error rate of 1% is expected.
Factors affecting the error rate include non-Roman typefaces and font size.
By comparison, the Internet Archive search allows full text search on one item at a time.
It does not offer simultaneous full text search of multiple items within the MHL.
Additionally, the Internet Archive does not index every page of every text.
For this reason, search results may vary between the two tools.
The results from this tool are more comprehensive.
What you will and won't find
In addition to OCR errors, results are influenced by the completeness of the descriptive information (metadata) provided by the contributing libraries.
We know, for example, that for 4,000 items in the MHL, no date has been provided.
There is no full text for video items.
Serial publications present special problems: volume numbers and volume dates are not always complete or uniformly formatted.
For each volume a second date may appear ("Date").
This indicates the first year of publication.
How to Search
Each field is labeled with the behavior it applies:
Primary Keywords Search
- The main search field applies a "best effort" approach to finding results. Items with the best match of the most number of terms are returned.
Publication Date Range
- From - To
- Use either or both fields to enter year(s) to filter by. Note that using only either a "from" OR "to" value (rather than both) may result in
results showing items which have non-standardized year values (ex. "2016-11"). When applied, results lacking a "Date" value will be excluded.
- ALL of these words
- This field applies an "AND" condition to multiple words. Example: human medicine is applied as human AND medicine
- Enter a numeric value (any positive integer) to apply a proximity condition to the "ALL" filter (only). The entered keywords must all appear within (n) characters of each other. Blank or zero (0) means no proximity will be applied.
- ANY of these words
- This field applies an "OR" condition to multiple words. Example: human medicine is applied as human OR medicine
- EXACT phrase
- This field applies an exact phrased condition to multiple words. Example: human medicine is applied as "human medicine"
- NONE of these words
- This field applies an exclusionary condition; multiple words are treated using "AND". Example: human medicine is applied as NOT human AND NOT medicine
Note: The advanced keywords fields are purposefully designed to eliminate the need to add logical operators to your queries (AND, OR, "", (), etc.). Including these in your queries may produce undesired results.
All field-specific filters apply a phrased search limited to that field. Example: human medicine in Title contains is applied as TITLE CONTAINS "human medicine"
Faceted Selection Keywords
Facet filters such as Languages and Media Types. Simply click any facet choice to apply, click again to de-apply.
Note that facets show ONLY the available options and count for the current result set, based on the current keyword(s) search.
- Show full details
- By default, results are shown in a summary format. Enable this option to see additional data fields. Note that this option does NOT change the current result set.
- Sort by
- Choose a sort order and direction. "Relevancy" is based on a scoring algorithm which accounts for the number of times keywords appear and applies weighting factors to certain fields such as the title.
- Download as
- Search results may be downloaded in other formats, as shown and per the listed limit. Note that the limit is from the first page of results, regardless of the currently shown page.
Tips and Notes
- Use of multiple filters are cumulative - using more than one kind of filter applies an "AND" condition between the filters.
- Selections within a specific filter, such as the various Languages, apply an "OR" condition between them.
- The number shown within a filter selection is the count of that value within the current result set.
- Use the "enter" key within any text-based filter field to update the results.
Feedback and Help
We need your feedback!
If you are having problems using the tool or would like to suggest improvements, please contact us at