Advanced Method 2:
Stack your query one step at a time (iterative searching) using Preview/Index

Build your search one term at a time on the Preview/Index page.

• The text box at the top of the page shows your active query.
• Preview button shows how many hits your search retrieves
• Go button displays the records retrieved by your search


• The bottom area of the page is like a worksheet, where you can enter a term of interest, select the desired search field, and use any (or all) of the following:
• Index button to browse the index of the field and select one or more terms
• AND, OR, NOT buttons to append selected terms to the active query
  (If multiple terms are selected from the index window, they will be ORed together before being appended to the active query)

I'd like to retrieve human nucleotide sequences associated with colon cancer.

Demo:  Open Entrez CoreNucleotide and select the Preview/Index option beneath the search box. Enter one term or phrase from your query at a time in the bottom text box, selecting the desired search field in each case. Use the Boolean AND, OR, NOT buttons to add each term to your active query at the top of the page. Step 1: enter colon cancer in the text box at the bottom of the page select Title as search field Press AND to add the term to the active query box at the top of the page Step 2: enter human in the text box at the bottom of the page select Organism as search field Press AND to add the term to the active query box at the top of the page Step 3: press Preview to see how many hits your search retrieves OR press Go to view the records retrieved by your search

Important note: This search method retrieves the same number of hits as advanced method #1 because it is just another way to do the same seach. However, it offers a very useful feature: INDEX button allows you to browse the Index of any search field If you select a search field and press the Index button without entering a term, you will be taken to the top of the index. If you enter a term first, you will be taken to that part of the index. shows the number of records that contain each term allows you to see the syntax of terms in special fields, such as Properties, Modification Date, and other fields in which the terms are entered in a special way allows you to select a range of terms (using the Shift key while selecting the first and last term) or multiple terms that do not fall within a range (using the Control key while selecting each desired term). The terms you select will be OR'ed together, and then added to the query in the active search box using whatever Boolean option you select (AND/OR/NOT)