diff --git a/README.md b/README.md
index 17478f7..6808e64 100644
--- a/README.md
+++ b/README.md
@@ -114,7 +114,7 @@ Here are a few examples of `RangeBounds` and whether they are valid:
 | 0..1           | YES   |
 | 9..8           | NO    |
 | (0.4)..=(-0.2) | NO    |
-| ..-3           | YES   |
+| ..(-3)         | YES   |
 | 0.0003..       | YES   |
 | ..             | YES   |
 | 400..=400      | YES   |
diff --git a/src/lib.rs b/src/lib.rs
index ff332b2..61a1e14 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -103,6 +103,30 @@ along with range_bounds_map. If not, see <https://www.gnu.org/licenses/>.
 //!
 //! ### Invalid RangeBounds
 //!
+//! Within this crate, not all `RangeBounds` are considered valid
+//! `RangeBounds`. The definition of the validity of a `RangeBounds` used
+//! within this crate is that a `RangeBounds` is only valid if it contains
+//! at least one value of the underlying domain.
+//!
+//! For example, `4..6` is considered valid as it contains the values `4`
+//! and `5`, however, `4..4` is considered invalid as it contains no
+//! values. Another example of invalid `RangeBounds` are those with
+//! `start_bound()`s with greater values than their `end_bound()`s, such
+//! as `5..2` or `100..=40`.
+//!
+//! Here are a few examples of `RangeBounds` and whether they are valid:
+//!
+//! | `RangeBounds`  | Valid |
+//! | -------------- | ----- |
+//! | 0..0           | NO    |
+//! | 0..1           | YES   |
+//! | 9..8           | NO    |
+//! | (0.4)..=(-0.2) | NO    |
+//! | ..(-3)         | YES   |
+//! | 0.0003..       | YES   |
+//! | ..             | YES   |
+//! | 400..=400      | YES   |
+//!
 //! ### Overlap
 //!
 //! Two `RangeBounds` are "overlapping" if there exists a point that is
@@ -120,6 +144,11 @@ along with range_bounds_map. If not, see <https://www.gnu.org/licenses/>.
 //! When a `RangeBounds` "merges" other `RangeBounds` it absorbs them
 //! to become larger.
 //!
+//! ### Further Reading
+//!
+//! See Wikipedia's article on Intervals:
+//! <https://en.wikipedia.org/wiki/Interval_(mathematics)>
+//!
 //! # Improvements/Caveats
 //!
 //! - Missing some functions common to BTreeMap and BTreeSet like:
@@ -155,6 +184,7 @@ along with range_bounds_map. If not, see <https://www.gnu.org/licenses/>.
 //! - <https://docs.rs/rangemap>
 //!   Very similar to this crate but can only use [`Range`]s and
 //!   [`RangeInclusive`]s as keys in it's `map` and `set` structs (separately).
+//! - <https://docs.rs/btree-range-map>
 //! - <https://docs.rs/ranges>
 //!   Cool library for fully-generic ranges (unlike std::ops ranges), along
 //!   with a `Ranges` datastructure for storing them (Vec-based