diff --git a/es2020.md b/es2020.md
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+This document specifies the extensions to the core ESTree AST types to support the ES2020 grammar.
+
+# Literal
+
+```js
+extend interface Literal <: Expression {
+    type: "Literal";
+    value: string | boolean | null | number | RegExp | bigint;
+}
+```
+
+- `value` property can be a `BigInt` value to represent `BigInt` literals
+  such as `100n`.
+
+## BigIntLiteral
+
+```js
+interface BigIntLiteral <: Literal {
+  bigint: string;
+}
+```
+
+- `bigint` property is the string representation of the `BigInt` value.
+  It doesn't include the suffix `n`.
+- In environments that don't support `BigInt` values, `value` property will be
+  `null` as the `BigInt` value can't be represented natively.
+
+# Expressions
+
+## ImportExpression
+
+```js
+interface ImportExpression <: Expression {
+  type: "ImportExpression";
+  source: Expression;
+}
+```
+
+- `ImportExpression` node represents Dynamic Imports such as `import(source)`.
+  The `source` property is the importing source as similar to [ImportExpression]
+  node, but it can be an arbitrary expression node.
+
+[ImportExpression]: es2015.md#importdeclaration
diff --git a/experimental/import-expression.md b/experimental/import-expression.md
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-# [Dynamic Import Expression](https://github.com/domenic/proposal-dynamic-import)
-
-## Import
-
-```js
-interface Import <: Node {
-    type: "Import";
-}
-
-interface CallExpression <: Expression {
-  callee: Expression | Super | Import;
-}
-```