Lesson 4 of 6 · 15 min · Checked on 10 October 2026
Researching with AI without being fooled: sources and citations
By the end of this lesson you will be able to:
- Tell an answer given from memory from an answer with search switched on
- Ask for sources and open them to confirm that they really say what is claimed
- Apply the rule: important fact = official source or two independent sources
A deadline that had already passed
Mr António wants to put solar panels on his house and has heard about a grant. He asks the AI: "Until when can I apply for the solar panel grant in the Azores?" The answer comes ready: a date, a maximum amount, the documents to attach. All very tidy.
His grandson is suspicious and asks him to repeat it with search switched on. This time the answer comes with two links. The first is a news item from two years ago: the date the AI had given was from that old notice. The second is the grant's official page, with this year's notice. The deadline is different, and so is the amount.
The AI did not lie on purpose. The first time it answered from memory. The second time it went to look, but mixed an old page with a new one. Only opening the sources showed the difference.
From memory or with search
An AI can answer in two ways:
- From memory. It uses what it learned in training, up to its cut-off date (Level 1, lesson 3). It does not know what changed afterwards. If it gives links, they may be invented.
- With search switched on. It goes to the internet, reads a few pages, summarises them and shows the links. It is much better for things that are current. But it can pick old or unreliable pages, misread them, and mix what one says with what another says.
How do you tell which one it was? Links or small numbers ([1], [2]) next to the sentences are a sign, not proof: the tool can write a link from memory, and the link may not even exist. Check the tool's search log (many show “Searching…” and the pages consulted) and open the sources. If there is none of that, it was from memory.
Asking for sources, and opening them
When the subject is serious, ask for sources in the request itself:
Search the internet and answer: [your question]. For each important fact (dates, deadlines, amounts, opening hours, addresses), give the source with a link. Prefer official sources: government websites, the town council, the service itself. Tell me the date of each page, if it shows one. If the sources disagree, tell me where they disagree.
Then open the sources for the facts you are going to use. In each one, confirm three things:
- Is it from who it says it is? Look at the address. An official website is not a blog or a page that repeats news.
- Does it really say that? Look in the page for the date or the number.
- Is it current? Check the date of the page or the year of the notice.
Watch out
The citation may exist and not say that. The AI puts a real link next to a sentence, but the page is about another year, another grant or another region. In the Azores and Madeira there are many rules of their own, and the AI often mixes what applies on the mainland with what applies on the islands.
Tip
To find a date on a long page, use "Find on page": on a computer, Ctrl+F (on a Mac, Cmd+F); on a phone, it is in the browser menu. You type the number or the word and the browser takes you there.
Three everyday cases
The opening hours of a public service. The AI may give the hours from an old page or from a website that gathers addresses from everywhere. Municipal holidays, days before holidays and building works change everything. Official source: the service's own website, or a phone call.
The deadline of an application. Deadlines are extended, notices change from year to year and news items copy each other with errors. Official source: the notice or the rules published by whoever gives the grant.
A medicine. The AI helps you understand difficult words in the leaflet. But the dose, the contraindications and what must not be taken at the same time are confirmed in the leaflet in your own package, with the pharmacist or with the doctor. If in doubt, the SNS 24 line, the national health line, answers on 808 24 24 24 (if you are in Portugal; elsewhere use your country's equivalent).
The rule
Important fact = the official source, or two independent sources.
Independent means that each one reached the information in its own way. Two news items that copy the same press release count as one. Two AIs saying the same is not enough either: they may have read the same wrong page. When there is an official source, it rules, as long as it is the current version.
Tip
Ask the AI for the exact sentence: "Copy the sentence from the source where that deadline appears." Then look for that sentence on the page. If it is not there, the deadline is not confirmed.
Search tools, today
This is how it looks on 6 October 2026; your screen may differ.
Perplexity was built with search in mind: it answers and shows the source for each part. ChatGPT, Claude, Gemini, Copilot and Le Chat also search the internet. In some, search switches on by itself when the question is about current things; in others, there is a button or an option with a name like "search" or "web".
Several also have a deep research mode: the AI spends a few minutes reading many pages and hands over a report with sources. It is handy for comparing options or gathering scattered information. The rules are the same: more sources do not mean more truth, and the important ones are opened one by one. What each version includes is on the Current state page.
Exercise
How I know it worked an answer with at least two sources, one of them opened and checked by you. You can say whether the page is official, whether the deadline or the amount is there and what date the page is from.
If it didn't work
- Did the answer come without sources? Search was not switched on. Look for the button or write "Search the internet before answering". If your tool does not search, try another.
- Does the link not open, or give an error? The page may have moved or may have been invented. Treat the fact as unconfirmed.
- Does the page not say that? Reply: "Source [2] does not say that. Where is that information?" And go to the official source yourself.
- Did only news items and blogs come back? "Give me only official sources: government, town council or service websites." Many Portuguese government websites end in gov.pt.
Videos
An official Claude video on why models hallucinate, how to spot the risk and which verification strategies to use.
Test what you learned
Corrections to this lesson (1)
- : Second external review: links and [1] numbers are a sign of a search, not proof; check the tool's search log and open the sources.