Literature search help

How to use the literature search

The literature search provides a simple query building tool as well as a full-fledged query language for more sophisticated searches.

The following features are supported:

Using the query building tool

The easiest way to use the search is to use the query building tool. It is located directly beneath the query box. Simply enter your search terms in the appropriate boxes and press “Build query” or the Return key on your keyboard. This will build the query with your search terms for you and place it in the query box. Pressing “Search” or using the Return key again runs the search.

You can also make changes to the generated query by editing it directly in the query box. Just remember that manual changes to the query will not be reflected in the building tool. If you press “Build query” again, the content of the query box will be overwritten. Also note that you cannot modify your search in the building tool after running it.

To add or remove search terms, use the “Add” and “Remove” buttons. Pressing “Add” will insert a new line underneath the current line. Empty lines will be ignored, so there is no need to remove them manually.

The building tool constructs the query so that all lines are joined with the selected logical operator. It is important to note that groups of OR’d terms are automatically enclosed in brackets. That way, if you specify multiple groups of OR’d terms and join them with AND or NOT, the query works as expected. That is because the AND and NOT operators have a higher precedence than the OR operator. For instance, if you enter the keywords “electrosmog” and “oxidative stress” joined with OR and the author “Wright W” joined with AND, the resulting query will find articles by “Wright W” that contain either “electrosmog” or “oxidative stress” or both terms.

Search fields

The literature search provides the following search fields:

“All fields”: a pseudofield that functions as a wildcard. It allows you to search all available fields. This includes the fields listed here as well as additional fields that can not be individually selected such as author keywords or MeSH terms.

“Author/organization”: this field allows you to search for articles written by specific authors or published by specific organizations (e.g., ICNIRP or WHO). The EMF-Portal database only collects surnames and initials of given names. Initials are specified without periods and placed after the surname. For instance, “William Quentin Wright” is indexed as “Wright WQ”. Initials are optional, i.e. “Wright W” or just “Wright” will also match “Wright WQ”. However, “Wright Q” will not work. Additionally, double or hyphenated names can be found by just specifying one part of the name, e.g., “Zeta-Jones” will also be found by searching for either “Zeta” or “Jones”.

“Year of publication”: this field allows you to search for articles published in a specific year or period. To specify a period, put a hyphen between the years. For instance, “2010-2020” will find all articles published between 2010 and 2020. When specifying a period, you may omit either the left or the right boundary. For instance, “2010-“ will match all articles published since 2010.

“Journal/book”: this field allows you to search for articles published in specific journals or books. To search for articles published in a particular journal, specify the name of the journal, the abbreviation, or one of its ISSNs (p-ISSN, e-ISSN, or ISSN-L). Names do not have to be entered completely. For instance, “Biochemistry” will also match “Journal of Biochemistry”. However, “Chemistry” will not match “Biochemistry”.

To search for articles published in a particular book, specify the book’s title. As with journal names, book titles do not have to be entered completely.

“Title”: this field allows you to search article and book titles. You can search for specific terms or complete titles.

“Title/abstract”: this field allows you to search article and book titles as well as abstracts.

“Author/organization (exact)”: this field is equivalent to the “Author/organization” field except that it will not match parts of double or hyphenated names.

“Journal/book (exact)”: this field is equivalent to the “Journal/book” field except that it will not match partial journal names or book titles.

“New articles since XX days”: this field searches for articles that were added to the EMF-Portal database within the last XX days, where XX can be a number between 1 and 99.

“Identifier”: this field searches for article and book identifiers. Currently supported are DOI and ISBN as well as article identifiers from other databases, namely PubMed, IEEE Xplore Digital Library, and Web of Science. ISSNs can be used in the “Journal/book” field (see above). Please be advised that the EMF-Portal database does not systematically collect all identifiers from other databases. Hence, it is best to search for an article via its DOI.

“Topic”: all articles in the EMF-Portal database are assigned to one of the following topics:

“Frequency range”: all articles in the EMF-Portal database are classified according to the examined frequency range:

Logical operators

The literature search provides three logical operators you can use to combine search terms: AND, OR, and NOT.


The AND operator is used to combine two terms so that only articles that contain both terms are matched. For instance, the query electrosmog AND "oxidative stress" will only match articles that contain both the term “electrosmog” and the term “oxidative stress”. Articles that contain only one of the two terms are not included.

AND is the default operator. It will be used implicitly whenever you enter two terms without an operator between them. Consequently, the query oxidative stress (without quotation marks) is equivalent to oxidative AND stress, i.e. it will match articles that contain both the term “oxidative” and the term “stress”, but not necessarily next to each other. If you want to search for the phrase “oxidative stress” instead, you have to put it in quotation marks.


The OR operator is used to combine two terms so that articles that contain at least one of the terms are matched. For instance, the query cancer OR tumor will match articles that contain either the term “cancer” or the term “tumor” or both terms.

Note that the OR operator has a lower precedence than the AND operator, i.e. expressions joined with AND will be evaluated before expressions joined with OR. For instance, the query author=Wright AND electrosmog OR "oxidative stress" will match articles by Wright that contain the term “electrosmog” plus all articles that contain the term “oxidative stress” regardless of whether Wright is the author or not. To find only articles by Wright, you have to put the keywords in brackets: author=Wright AND (electrosmog OR "oxidative stress")


The NOT operator is used to combine two terms so that articles that contain the first term are matched if they do not contain the second term. For instance, the query electrosmog NOT "oxidative stress" will match articles that contain the term “electrosmog” and do not contain the term “oxidative stress”.

Note that the operators are case-sensitive, so, for instance, “and” (lower case) will be interpreted as a search term instead of the AND operator.

Prefix searches

The literature search supports prefix searches. A prefix search is a kind of wildcard search that matches words starting with a specific combination of characters. You can perform a prefix search by putting an asterisk at the end of your search term. For instance, a search for “expos*” will match all words that begin with “expos”, such as “exposure”, “exposimeter”, and “exposome”.

Note that the number of characters before the wildcard has to be at least 4. Otherwise, the search term will be treated as a regular search term and the asterisk will simply be treated as punctuation.


The literature search automatically applies stemming, which means that it searches for all terms with the same linguistic root (stem) as the query term. For instance, searching for “mouse” will also match “mice” and vice versa. Searching for “expose” will also match “exposed”, “exposes”, and “exposing”. However, the noun “exposure” will not be matched. You can use the OR operator (expose OR exposure) or a prefix search (expos*) to include the noun as well.

The following fields support stemming: “Journal/book”, “Title”, “Title/abstract”, and the “All fields” pseudofield. Note that stemming is currently supported for the English language only.

Synonyms and translations

The literature search automatically includes synonyms and translations of technical terms from our glossary. For instance, searching for “mobile phone” will also match the synonymous terms “mobile telephone”, “cell phone”, “cellular phone”, “cellular telephone”, and “smart phone”, as well as the respective German und Japanese translations. Stemming is automatically applied to all synonyms (English only).

The following fields support synonyms and translations: “Journal/book”, “Title”, “Title/abstract”, and the “All fields” pseudofield.

Writing queries yourself

The best way to learn how to write your own queries is to first use the query building tool and have a look at its output. The syntax of the query language is not complicated. A query consists of the following elements: predicates, logical operators, and brackets.

Predicates are just your search terms. They can be prefixed with a field name followed by an equals sign to indicate which field to search. For instance, to search for articles published in the journal Bioelectromagnetics, you would type publication=Bioelectromagnetics. There must be no spaces around the equals sign. Field names are not case-sensitive. To search for phrases, i.e. search terms that contain whitespace, enclose the phrase in quotation marks. For instance, to search for titles containing the phrase “oxidative stress”, use the query title="oxidative stress". If no field is specified, all fields will be searched. You can explicitly search all fields by using the wildcard “all”, e.g. all="oxidative stress".

Note that the field names in the query are a bit different that the names you see in the query building tool. The following table aids in translating fields names. Additionally, field names can be abbreviated to save you some typing.

Field Query field name Query field abbreviation
All fields all
Author/organization author a
Year of publication year y
Journal/book publication p
Title title t
Title/abstract ta
Author/organization (exact) authorexact aex
Journal/book (exact) publicationexact pex
New articles since XX days entry e
Identifier id
Topic topic to
Frequency range frequency f

Similar to field names, topics and frequency ranges are encoded in a specific way, which the following tables shows:

Topic or frequency range Query name
Experimental studies experimental
Epidemiological studies epidemiological
Electromagnetic interference electromagnetic_interference
Technical/dosimetric studies technical_dosimetric
Medical applications medical_application
Electrical injuries electrical_injury
Laws, recommendations, guidelines law_recommendation_guideline
Reviews, surveys, summaries review_survey_summary
Risk communication risk_communication
Other other
Radio frequency (≥ 10 MHz) radio_frequency
Mobile communications mobile_communications
Low frequency (< 10 MHz) low_frequency
Power frequencies (50/60 Hz) power_lines
Direct current/static fields (DC) dc
Electric current electric_current


The literature search currently imposes the following restrictions:

It is important to note that overly long queries might not work even if they have fewer than 10,000 characters. The reason for this is that browsers, web and proxy servers, and other middleware on the internet might not support URLs that long. Generally speaking, if you keep your query below 2,000 characters, you should be safe. If necessary, you can use field abbreviations to save some space.